auto_index/test/test1.gold

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<chapter xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" id="boost_typetraits" rev:last-revision="$Date: 2008-11-28 12:41:45 +0000 (Fri, 28 Nov 2008) $">
  <chapterinfo><author>
      <firstname>various</firstname> <surname>authors</surname>
    </author><copyright>
      <year>2000</year> <year>2006</year> <holder>Adobe Systems Inc, David Abrahams,
      Steve Cleary, Beman Dawes, Aleksey Gurtovoy, Howard Hinnant, Jesse Jones, Mat
      Marcus, Itay Maman, John Maddock, Alexander Nasonov, Thorsten Ottosen, Robert
      Ramey and Jeremy Siek</holder>
    </copyright><legalnotice>
      <para>
        Distributed under the Boost Software License, Version 1.0. (See accompanying
        file LICENSE_1_0.txt or copy at <ulink url="http://www.boost.org/LICENSE_1_0.txt">http://www.boost.org/LICENSE_1_0.txt</ulink>)
      </para>
    </legalnotice></chapterinfo>
  <title>Boost.TypeTraits</title>
  <para>
    A printer-friendly <ulink url="http://svn.boost.org/svn/boost/sandbox/pdf/type_traits/release/type_traits.pdf">PDF
    version of this manual is also available</ulink>.
  </para>
  <section id="boost_typetraits.intro"><indexterm type="test_index_1"><primary>type-traits</primary><secondary>Introduction</secondary></indexterm><indexterm><primary>Introduction</primary><secondary>type-traits</secondary></indexterm><indexterm type="test_index_1"><primary>type-traits</primary><secondary>Introduction</secondary></indexterm><indexterm><primary>Introduction</primary><secondary>type-traits</secondary></indexterm><indexterm type="test_index_1"><primary>type-traits</primary><secondary>Introduction</secondary></indexterm><indexterm><primary>Introduction</primary><secondary>type-traits</secondary></indexterm>
    <title><link linkend="boost_typetraits.intro"> Introduction</link></title>
    <para>
      The Boost type-traits library contains a set of very specific traits classes,
      each of which encapsulate a single trait from the C++ type system; for example,
      is a type a pointer or a reference type? Or does a type have a trivial constructor,
      or a const-qualifier?
    </para>
    <para>
      The type-traits classes share a unified design: each class inherits from a
      the type <link linkend="boost_typetraits.reference.integral_constant">true_type</link>
      if the type has the specified property and inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>
      otherwise.
    </para>
    <para>
      The type-traits library also contains a set of classes that perform a specific
      transformation on a type; for example, they can remove a top-level const or
      volatile qualifier from a type. Each class that performs a transformation defines
      a single typedef-member <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">type</phrase></computeroutput>
      that is the result of the transformation.
    </para>
  </section>
  <section id="boost_typetraits.background"><indexterm type="test_index_2"><primary>type-traits</primary><secondary>Background and Tutorial</secondary></indexterm><indexterm><primary>Background and Tutorial</primary><secondary>type-traits</secondary></indexterm><indexterm type="test_index_2"><primary>type-traits</primary><secondary>Background and Tutorial</secondary></indexterm><indexterm><primary>Background and Tutorial</primary><secondary>type-traits</secondary></indexterm><indexterm type="class_name"><primary>remove_extent</primary><secondary>Background and Tutorial</secondary></indexterm><indexterm><primary>Background and Tutorial</primary><secondary>remove_extent</secondary></indexterm><indexterm type="class_name"><primary>is_pointer</primary><secondary>Background and Tutorial</secondary></indexterm><indexterm><primary>Background and Tutorial</primary><secondary>is_pointer</secondary></indexterm><indexterm type="class_name"><primary>is_void</primary><secondary>Background and Tutorial</secondary></indexterm><indexterm><primary>Background and Tutorial</primary><secondary>is_void</secondary></indexterm><indexterm type="test_index_2"><primary>type-traits</primary><secondary>Background and Tutorial</secondary></indexterm><indexterm><primary>Background and Tutorial</primary><secondary>type-traits</secondary></indexterm><indexterm type="test_index_2"><primary>type-traits</primary><secondary>Background and Tutorial</secondary></indexterm><indexterm><primary>Background and Tutorial</primary><secondary>type-traits</secondary></indexterm><indexterm type="test_index_2"><primary>type-traits</primary><secondary>Background and Tutorial</secondary></indexterm><indexterm><primary>Background and Tutorial</primary><secondary>type-traits</secondary></indexterm>
    <title><link linkend="boost_typetraits.background"> Background and Tutorial</link></title>
    <para>
      The following is an updated version of the article "C++ Type traits"
      by John Maddock and Steve Cleary that appeared in the October 2000 issue of
      <ulink url="http://www.ddj.com">Dr Dobb's Journal</ulink>.
    </para>
    <para>
      Generic programming (writing code which works with any data type meeting a
      set of requirements) has become the method of choice for providing reusable
      code. However, there are times in generic programming when "generic"
      just isn't good enough - sometimes the differences between types are too large
      for an efficient generic implementation. This is when the traits technique
      becomes important - by encapsulating those properties that need to be considered
      on a type by type basis inside a traits class, we can minimize the amount of
      code that has to differ from one type to another, and maximize the amount of
      generic code.
    </para>
    <?dbfo keep-together="auto" ?>
    <para>
      <indexterm>
        <primary>Foo1</primary>
      </indexterm>
      Consider an example: when working with character strings, one common operation
      is to determine the length of a null terminated string. Clearly it's possible
      to write generic code that can do this, but it turns out that there are much
      more efficient methods available: for example, the C library functions <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">strlen</phrase></computeroutput> and <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">wcslen</phrase></computeroutput>
      are usually written in assembler, and with suitable hardware support can be
      considerably faster than a generic version written in C++. The authors of the
      C++ standard library realized this, and abstracted the properties of <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">char</phrase></computeroutput> and <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">wchar_t</phrase></computeroutput>
      into the class <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">char_traits</phrase></computeroutput>.
      Generic code that works with character strings can simply use <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">char_traits</phrase><phrase role="special">&lt;&gt;::</phrase><phrase role="identifier">length</phrase></computeroutput> to determine the length of a null
      terminated string, safe in the knowledge that specializations of <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">char_traits</phrase></computeroutput> will use the most appropriate
      method available to them.
    </para>
    <anchor id="boost_typetraits.background.type_traits"/>
    <bridgehead renderas="sect4">
      <link linkend="boost_typetraits.background.type_traits">Type Traits</link>
    </bridgehead>
    <para>
      Class <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">char_traits</phrase></computeroutput> is a classic
      example of a collection of type specific properties wrapped up in a single
      class - what Nathan Myers termed a <emphasis>baggage class</emphasis><link linkend="background.references">[1]</link>. In the Boost type-traits library,
      we<link linkend="background.references">[2]</link> have written a set of very
      specific traits classes, each of which encapsulate a single trait from the
      C++ type system; for example, is a type a pointer or a reference type? Or does
      a type have a trivial constructor, or a const-qualifier? The type-traits classes
      share a unified design: each class inherits from a the type <link linkend="boost_typetraits.reference.integral_constant">true_type</link>
      if the type has the specified property and inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>
      otherwise. As we will show, these classes can be used in generic programming
      to determine the properties of a given type and introduce optimizations that
      are appropriate for that case.
    </para>
    <para>
      The type-traits library also contains a set of classes that perform a specific
      transformation on a type; for example, they can remove a top-level const or
      volatile qualifier from a type. Each class that performs a transformation defines
      a single typedef-member <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">type</phrase></computeroutput>
      that is the result of the transformation. All of the type-traits classes are
      defined inside namespace <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">boost</phrase></computeroutput>;
      for brevity, namespace-qualification is omitted in most of the code samples
      given.
    </para>
    <anchor id="boost_typetraits.background.implementation"/>
    <bridgehead renderas="sect4">
      <link linkend="boost_typetraits.background.implementation">Implementation</link>
    </bridgehead>
    <para>
      There are far too many separate classes contained in the type-traits library
      to give a full implementation here - see the source code in the Boost library
      for the full details - however, most of the implementation is fairly repetitive
      anyway, so here we will just give you a flavor for how some of the classes
      are implemented. Beginning with possibly the simplest class in the library,
      <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_void</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase></computeroutput> inherits
      from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>
      only if <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput> is <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">void</phrase></computeroutput>.
    </para>
    
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">typename</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase> 
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_void">is_void</link> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <link linkend="boost_typetraits.reference.integral_constant">false_type</link><phrase role="special">{};</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;&gt;</phrase> 
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_void">is_void</link><phrase role="special">&lt;</phrase><phrase role="keyword">void</phrase><phrase role="special">&gt;</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <link linkend="boost_typetraits.reference.integral_constant">true_type</link><phrase role="special">{};</phrase>
</programlisting>
    <para>
      Here we define a primary version of the template class <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.is_void">is_void</link></computeroutput>,
      and provide a full-specialization when <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>
      is <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">void</phrase></computeroutput>. While full specialization
      of a template class is an important technique, sometimes we need a solution
      that is halfway between a fully generic solution, and a full specialization.
      This is exactly the situation for which the standards committee defined partial
      template-class specialization. As an example, consider the class <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">boost</phrase><phrase role="special">::</phrase><phrase role="identifier">is_pointer</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase></computeroutput>:
      here we needed a primary version that handles all the cases where T is not
      a pointer, and a partial specialization to handle all the cases where T is
      a pointer:
    </para>
    
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">typename</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase> 
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_pointer">is_pointer</link> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <link linkend="boost_typetraits.reference.integral_constant">false_type</link><phrase role="special">{};</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">typename</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase> 
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_pointer">is_pointer</link><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">*&gt;</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <link linkend="boost_typetraits.reference.integral_constant">true_type</link><phrase role="special">{};</phrase>
</programlisting>
    <para>
      The syntax for partial specialization is somewhat arcane and could easily occupy
      an article in its own right; like full specialization, in order to write a
      partial specialization for a class, you must first declare the primary template.
      The partial specialization contains an extra &lt;...&gt; after the class name
      that contains the partial specialization parameters; these define the types
      that will bind to that partial specialization rather than the default template.
      The rules for what can appear in a partial specialization are somewhat convoluted,
      but as a rule of thumb if you can legally write two function overloads of the
      form:
    </para>
    
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">void</phrase> <phrase role="identifier">foo</phrase><phrase role="special">(</phrase><phrase role="identifier">T</phrase><phrase role="special">);</phrase>
<phrase role="keyword">void</phrase> <phrase role="identifier">foo</phrase><phrase role="special">(</phrase><phrase role="identifier">U</phrase><phrase role="special">);</phrase>
</programlisting>
    <para>
      Then you can also write a partial specialization of the form:
    </para>
    
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">typename</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">class</phrase> <phrase role="identifier">c</phrase><phrase role="special">{</phrase> <phrase role="comment">/*details*/</phrase> <phrase role="special">};</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">typename</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">class</phrase> <phrase role="identifier">c</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">U</phrase><phrase role="special">&gt;{</phrase> <phrase role="comment">/*details*/</phrase> <phrase role="special">};</phrase>
</programlisting>
    <para>
      This rule is by no means foolproof, but it is reasonably simple to remember
      and close enough to the actual rule to be useful for everyday use.
    </para>
    <para>
      As a more complex example of partial specialization consider the class <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_extent</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase></computeroutput>. This
      class defines a single typedef-member <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">type</phrase></computeroutput>
      that is the same type as T but with any top-level array bounds removed; this
      is an example of a traits class that performs a transformation on a type:
    </para>
    
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">typename</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase> 
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.remove_extent">remove_extent</link>
<phrase role="special">{</phrase> <phrase role="keyword">typedef</phrase> <phrase role="identifier">T</phrase> <phrase role="identifier">type</phrase><phrase role="special">;</phrase> <phrase role="special">};</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">typename</phrase> <phrase role="identifier">T</phrase><phrase role="special">,</phrase> <phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">size_t</phrase> <phrase role="identifier">N</phrase><phrase role="special">&gt;</phrase> 
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.remove_extent">remove_extent</link><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">[</phrase><phrase role="identifier">N</phrase><phrase role="special">]&gt;</phrase>
<phrase role="special">{</phrase> <phrase role="keyword">typedef</phrase> <phrase role="identifier">T</phrase> <phrase role="identifier">type</phrase><phrase role="special">;</phrase> <phrase role="special">};</phrase>
</programlisting>
    <para>
      The aim of <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.remove_extent">remove_extent</link></computeroutput>
      is this: imagine a generic algorithm that is passed an array type as a template
      parameter, <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.remove_extent">remove_extent</link></computeroutput>
      provides a means of determining the underlying type of the array. For example
      <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_extent</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">[</phrase><phrase role="number">4</phrase><phrase role="special">][</phrase><phrase role="number">5</phrase><phrase role="special">]&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput> would evaluate to the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase><phrase role="special">[</phrase><phrase role="number">5</phrase><phrase role="special">]</phrase></computeroutput>. This example also shows that the number of
      template parameters in a partial specialization does not have to match the
      number in the default template. However, the number of parameters that appear
      after the class name do have to match the number and type of the parameters
      in the default template.
    </para>
    <anchor id="boost_typetraits.background.optimized_copy"/>
    <bridgehead renderas="sect4">
      <link linkend="boost_typetraits.background.optimized_copy">Optimized copy</link>
    </bridgehead>
    <para>
      As an example of how the type traits classes can be used, consider the standard
      library algorithm copy:
    </para>
    
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">typename</phrase> <phrase role="identifier">Iter1</phrase><phrase role="special">,</phrase> <phrase role="keyword">typename</phrase> <phrase role="identifier">Iter2</phrase><phrase role="special">&gt;</phrase>
<phrase role="identifier">Iter2</phrase> <phrase role="identifier">copy</phrase><phrase role="special">(</phrase><phrase role="identifier">Iter1</phrase> <phrase role="identifier">first</phrase><phrase role="special">,</phrase> <phrase role="identifier">Iter1</phrase> <phrase role="identifier">last</phrase><phrase role="special">,</phrase> <phrase role="identifier">Iter2</phrase> <phrase role="identifier">out</phrase><phrase role="special">);</phrase>
</programlisting>
    <para>
      Obviously, there's no problem writing a generic version of copy that works
      for all iterator types <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">Iter1</phrase></computeroutput>
      and <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">Iter2</phrase></computeroutput>; however, there are
      some circumstances when the copy operation can best be performed by a call
      to <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">memcpy</phrase></computeroutput>. In order to implement
      copy in terms of <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">memcpy</phrase></computeroutput> all
      of the following conditions need to be met:
    </para>
    <itemizedlist>
      <listitem>
        Both of the iterator types <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">Iter1</phrase></computeroutput>
        and <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">Iter2</phrase></computeroutput> must be pointers.
      </listitem>
      <listitem>
        Both <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">Iter1</phrase></computeroutput> and <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">Iter2</phrase></computeroutput> must point to the same type - excluding
        const and volatile-qualifiers.
      </listitem>
      <listitem>
        The type pointed to by <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">Iter1</phrase></computeroutput>
        must have a trivial assignment operator.
      </listitem>
    </itemizedlist>
    <para>
      By trivial assignment operator we mean that the type is either a scalar type<link linkend="background.references">[3]</link> or:
    </para>
    <itemizedlist>
      <listitem>
        The type has no user defined assignment operator.
      </listitem>
      <listitem>
        The type does not have any data members that are references.
      </listitem>
      <listitem>
        All base classes, and all data member objects must have trivial assignment
        operators.
      </listitem>
    </itemizedlist>
    <para>
      If all these conditions are met then a type can be copied using <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">memcpy</phrase></computeroutput> rather than using a compiler generated
      assignment operator. The type-traits library provides a class <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.has_trivial_assign">has_trivial_assign</link></computeroutput>,
      such that <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">has_trivial_assign</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is true only if T has a trivial assignment
      operator. This class "just works" for scalar types, but has to be
      explicitly specialised for class/struct types that also happen to have a trivial
      assignment operator. In other words if <link linkend="boost_typetraits.reference.has_trivial_assign">has_trivial_assign</link>
      gives the wrong answer, it will give the "safe" wrong answer - that
      trivial assignment is not allowable.
    </para>
    <para>
      The code for an optimized version of copy that uses <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">memcpy</phrase></computeroutput>
      where appropriate is given in <link linkend="boost_typetraits.examples.copy">the
      examples</link>. The code begins by defining a template function <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">do_copy</phrase></computeroutput> that performs a "slow but safe"
      copy. The last parameter passed to this function may be either a <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>
      or a <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">false_type</link></computeroutput>.
      Following that there is an overload of do<emphasis role="underline">copy that
      uses `memcpy`: this time the iterators are required to actually be pointers
      to the same type, and the final parameter must be a `</emphasis>_true_type<computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="special">.</phrase> <phrase role="identifier">Finally</phrase><phrase role="special">,</phrase> <phrase role="identifier">the</phrase> <phrase role="identifier">version</phrase>
      <phrase role="identifier">of</phrase> </computeroutput>copy<computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="identifier">calls</phrase>
      </computeroutput>do<emphasis role="underline">copy`, passing `</emphasis>_has_trivial_assign&lt;value_type&gt;()`
      as the final parameter: this will dispatch to the optimized version where appropriate,
      otherwise it will call the "slow but safe version".
    </para>
    <anchor id="boost_typetraits.background.was_it_worth_it_"/>
    <bridgehead renderas="sect4">
      <link linkend="boost_typetraits.background.was_it_worth_it_">Was it worth it?</link>
    </bridgehead>
    <para>
      It has often been repeated in these columns that "premature optimization
      is the root of all evil" <link linkend="background.references">[4]</link>.
      So the question must be asked: was our optimization premature? To put this
      in perspective the timings for our version of copy compared a conventional
      generic copy<link linkend="background.references">[5]</link> are shown in table
      1.
    </para>
    <para>
      Clearly the optimization makes a difference in this case; but, to be fair,
      the timings are loaded to exclude cache miss effects - without this accurate
      comparison between algorithms becomes difficult. However, perhaps we can add
      a couple of caveats to the premature optimization rule:
    </para>
    <itemizedlist>
      <listitem>
        If you use the right algorithm for the job in the first place then optimization
        will not be required; in some cases, memcpy is the right algorithm.
      </listitem>
      <listitem>
        If a component is going to be reused in many places by many people then optimizations
        may well be worthwhile where they would not be so for a single case - in
        other words, the likelihood that the optimization will be absolutely necessary
        somewhere, sometime is that much higher. Just as importantly the perceived
        value of the stock implementation will be higher: there is no point standardizing
        an algorithm if users reject it on the grounds that there are better, more
        heavily optimized versions available.
      </listitem>
    </itemizedlist>
    <table frame="all"> <title>Time taken to copy 1000 elements using `copy&lt;const
    T*, T*&gt;` (times in micro-seconds)</title>
    <tgroup cols="3">
      <thead>
        <row>
          <entry>
          <para>
            Version
          </para>
          </entry><entry>
          <para>
            T
          </para>
          </entry><entry>
          <para>
            Time
          </para>
          </entry>
        </row>
      </thead>
      <tbody>
        <row>
          <entry>
          <para>
            "Optimized" copy
          </para>
          </entry><entry>
          <para>
            char
          </para>
          </entry><entry>
          <para>
            0.99
          </para>
          </entry>
        </row>
        <row>
          <entry>
          <para>
            Conventional copy
          </para>
          </entry><entry>
          <para>
            char
          </para>
          </entry><entry>
          <para>
            8.07
          </para>
          </entry>
        </row>
        <row>
          <entry>
          <para>
            "Optimized" copy
          </para>
          </entry><entry>
          <para>
            int
          </para>
          </entry><entry>
          <para>
            2.52
          </para>
          </entry>
        </row>
        <row>
          <entry>
          <para>
            Conventional copy
          </para>
          </entry><entry>
          <para>
            int
          </para>
          </entry><entry>
          <para>
            8.02
          </para>
          </entry>
        </row>
      </tbody>
    </tgroup>
    </table> <anchor id="boost_typetraits.background.pair_of_references"/>
    <bridgehead renderas="sect4">
      <link linkend="boost_typetraits.background.pair_of_references">Pair of References</link>
    </bridgehead>
    <para>
      The optimized copy example shows how type traits may be used to perform optimization
      decisions at compile-time. Another important usage of type traits is to allow
      code to compile that otherwise would not do so unless excessive partial specialization
      is used. This is possible by delegating partial specialization to the type
      traits classes. Our example for this form of usage is a pair that can hold
      references <link linkend="background.references">[6]</link>.
    </para>
    <para>
      First, let us examine the definition of <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">pair</phrase></computeroutput>, omitting
      the comparison operators, default constructor, and template copy constructor
      for simplicity:
    </para>
    
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">typename</phrase> <phrase role="identifier">T1</phrase><phrase role="special">,</phrase> <phrase role="keyword">typename</phrase> <phrase role="identifier">T2</phrase><phrase role="special">&gt;</phrase> 
<phrase role="keyword">struct</phrase> <phrase role="identifier">pair</phrase> 
<phrase role="special">{</phrase>
<phrase role="keyword">typedef</phrase> <phrase role="identifier">T1</phrase> <phrase role="identifier">first_type</phrase><phrase role="special">;</phrase>
<phrase role="keyword">typedef</phrase> <phrase role="identifier">T2</phrase> <phrase role="identifier">second_type</phrase><phrase role="special">;</phrase>

<phrase role="identifier">T1</phrase> <phrase role="identifier">first</phrase><phrase role="special">;</phrase>
<phrase role="identifier">T2</phrase> <phrase role="identifier">second</phrase><phrase role="special">;</phrase>

<phrase role="identifier">pair</phrase><phrase role="special">(</phrase><phrase role="keyword">const</phrase> <phrase role="identifier">T1</phrase> <phrase role="special">&amp;</phrase> <phrase role="identifier">nfirst</phrase><phrase role="special">,</phrase> <phrase role="keyword">const</phrase> <phrase role="identifier">T2</phrase> <phrase role="special">&amp;</phrase> <phrase role="identifier">nsecond</phrase><phrase role="special">)</phrase>
<phrase role="special">:</phrase><phrase role="identifier">first</phrase><phrase role="special">(</phrase><phrase role="identifier">nfirst</phrase><phrase role="special">),</phrase> <phrase role="identifier">second</phrase><phrase role="special">(</phrase><phrase role="identifier">nsecond</phrase><phrase role="special">)</phrase> <phrase role="special">{</phrase> <phrase role="special">}</phrase>
<phrase role="special">};</phrase>
</programlisting>
    <para>
      Now, this "pair" cannot hold references as it currently stands, because
      the constructor would require taking a reference to a reference, which is currently
      illegal <link linkend="background.references">[7]</link>. Let us consider what
      the constructor's parameters would have to be in order to allow "pair"
      to hold non-reference types, references, and constant references:
    </para>
    <table frame="all"> <title>Required Constructor Argument Types</title>
    <tgroup cols="2">
      <thead>
        <row>
          <entry>
          <para>
            Type of <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T1</phrase></computeroutput>
          </para>
          </entry><entry>
          <para>
            Type of parameter to initializing constructor
          </para>
          </entry>
        </row>
      </thead>
      <tbody>
        <row>
          <entry>
          <para>
            T
          </para>
          </entry><entry>
          <para>
            const T &amp;
          </para>
          </entry>
        </row>
        <row>
          <entry>
          <para>
            T &amp;
          </para>
          </entry><entry>
          <para>
            T &amp;
          </para>
          </entry>
        </row>
        <row>
          <entry>
          <para>
            const T &amp;
          </para>
          </entry><entry>
          <para>
            const T &amp;
          </para>
          </entry>
        </row>
      </tbody>
    </tgroup>
    </table>
    <para>
      A little familiarity with the type traits classes allows us to construct a
      single mapping that allows us to determine the type of parameter from the type
      of the contained class. The type traits classes provide a transformation <link linkend="boost_typetraits.reference.add_reference">add_reference</link>, which
      adds a reference to its type, unless it is already a reference.
    </para>
    <table frame="all"> <title>Using add_reference to synthesize the correct constructor
    type</title>
    <tgroup cols="3">
      <thead>
        <row>
          <entry>
          <para>
            Type of <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T1</phrase></computeroutput>
          </para>
          </entry><entry>
          <para>
            Type of <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">const</phrase> <phrase role="identifier">T1</phrase></computeroutput>
          </para>
          </entry><entry>
          <para>
            Type of <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">add_reference</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">const</phrase> <phrase role="identifier">T1</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
          </para>
          </entry>
        </row>
      </thead>
      <tbody>
        <row>
          <entry>
          <para>
            T
          </para>
          </entry><entry>
          <para>
            const T
          </para>
          </entry><entry>
          <para>
            const T &amp;
          </para>
          </entry>
        </row>
        <row>
          <entry>
          <para>
            T &amp;
          </para>
          </entry><entry>
          <para>
            T &amp; [8]
          </para>
          </entry><entry>
          <para>
            T &amp;
          </para>
          </entry>
        </row>
        <row>
          <entry>
          <para>
            const T &amp;
          </para>
          </entry><entry>
          <para>
            const T &amp;
          </para>
          </entry><entry>
          <para>
            const T &amp;
          </para>
          </entry>
        </row>
      </tbody>
    </tgroup>
    </table>
    <para>
      This allows us to build a primary template definition for <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">pair</phrase></computeroutput>
      that can contain non-reference types, reference types, and constant reference
      types:
    </para>
    
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">typename</phrase> <phrase role="identifier">T1</phrase><phrase role="special">,</phrase> <phrase role="keyword">typename</phrase> <phrase role="identifier">T2</phrase><phrase role="special">&gt;</phrase> 
<phrase role="keyword">struct</phrase> <phrase role="identifier">pair</phrase> 
<phrase role="special">{</phrase>
<phrase role="keyword">typedef</phrase> <phrase role="identifier">T1</phrase> <phrase role="identifier">first_type</phrase><phrase role="special">;</phrase>
<phrase role="keyword">typedef</phrase> <phrase role="identifier">T2</phrase> <phrase role="identifier">second_type</phrase><phrase role="special">;</phrase>

<phrase role="identifier">T1</phrase> <phrase role="identifier">first</phrase><phrase role="special">;</phrase>
<phrase role="identifier">T2</phrase> <phrase role="identifier">second</phrase><phrase role="special">;</phrase>

<phrase role="identifier">pair</phrase><phrase role="special">(</phrase><phrase role="identifier">boost</phrase><phrase role="special">::</phrase><link linkend="boost_typetraits.reference.add_reference">add_reference</link><phrase role="special">&lt;</phrase><phrase role="keyword">const</phrase> <phrase role="identifier">T1</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase> <phrase role="identifier">nfirst</phrase><phrase role="special">,</phrase>
      <phrase role="identifier">boost</phrase><phrase role="special">::</phrase><link linkend="boost_typetraits.reference.add_reference">add_reference</link><phrase role="special">&lt;</phrase><phrase role="keyword">const</phrase> <phrase role="identifier">T2</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase> <phrase role="identifier">nsecond</phrase><phrase role="special">)</phrase>
<phrase role="special">:</phrase><phrase role="identifier">first</phrase><phrase role="special">(</phrase><phrase role="identifier">nfirst</phrase><phrase role="special">),</phrase> <phrase role="identifier">second</phrase><phrase role="special">(</phrase><phrase role="identifier">nsecond</phrase><phrase role="special">)</phrase> <phrase role="special">{</phrase> <phrase role="special">}</phrase>
<phrase role="special">};</phrase>
</programlisting>
    <para>
      Add back in the standard comparison operators, default constructor, and template
      copy constructor (which are all the same), and you have a <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">pair</phrase></computeroutput> that
      can hold reference types!
    </para>
    <para>
      This same extension could have been done using partial template specialization
      of <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">pair</phrase></computeroutput>, but to specialize
      <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">pair</phrase></computeroutput> in this way would require
      three partial specializations, plus the primary template. Type traits allows
      us to define a single primary template that adjusts itself auto-magically to
      any of these partial specializations, instead of a brute-force partial specialization
      approach. Using type traits in this fashion allows programmers to delegate
      partial specialization to the type traits classes, resulting in code that is
      easier to maintain and easier to understand.
    </para>
    <anchor id="boost_typetraits.background.conclusion"/>
    <bridgehead renderas="sect4">
      <link linkend="boost_typetraits.background.conclusion">Conclusion</link>
    </bridgehead>
    <para>
      We hope that in this article we have been able to give you some idea of what
      type-traits are all about. A more complete listing of the available classes
      are in the boost documentation, along with further examples using type traits.
      Templates have enabled C++ uses to take the advantage of the code reuse that
      generic programming brings; hopefully this article has shown that generic programming
      does not have to sink to the lowest common denominator, and that templates
      can be optimal as well as generic.
    </para>
    <anchor id="boost_typetraits.background.acknowledgements"/>
    <bridgehead renderas="sect4">
      <link linkend="boost_typetraits.background.acknowledgements">Acknowledgements</link>
    </bridgehead>
    <para>
      The authors would like to thank Beman Dawes and Howard Hinnant for their helpful
      comments when preparing this article.
    </para>
    <anchor id="background.references"/> <anchor id="boost_typetraits.background.references"/>
    <bridgehead renderas="sect4">
      <link linkend="boost_typetraits.background.references">References</link>
    </bridgehead>
    <orderedlist inheritnum="ignore" continuation="restarts">
      <listitem>
        Nathan C. Myers, C++ Report, June 1995.
      </listitem>
      <listitem>
        The type traits library is based upon contributions by Steve Cleary, Beman
        Dawes, Howard Hinnant and John Maddock: it can be found at www.boost.org.
      </listitem>
      <listitem>
        A scalar type is an arithmetic type (i.e. a built-in integer or floating
        point type), an enumeration type, a pointer, a pointer to member, or a const-
        or volatile-qualified version of one of these types.
      </listitem>
      <listitem>
        This quote is from Donald Knuth, ACM Computing Surveys, December 1974, pg
        268.
      </listitem>
      <listitem>
        The test code is available as part of the boost utility library (see algo_opt_examples.cpp),
        the code was compiled with gcc 2.95 with all optimisations turned on, tests
        were conducted on a 400MHz Pentium II machine running Microsoft Windows 98.
      </listitem>
      <listitem>
        John Maddock and Howard Hinnant have submitted a "compressed_pair"
        library to Boost, which uses a technique similar to the one described here
        to hold references. Their pair also uses type traits to determine if any
        of the types are empty, and will derive instead of contain to conserve space
        -- hence the name "compressed".
      </listitem>
      <listitem>
        This is actually an issue with the C++ Core Language Working Group (issue
        #106), submitted by Bjarne Stroustrup. The tentative resolution is to allow
        a "reference to a reference to T" to mean the same thing as a "reference
        to T", but only in template instantiation, in a method similar to multiple
        cv-qualifiers.
      </listitem>
      <listitem>
        For those of you who are wondering why this shouldn't be const-qualified,
        remember that references are always implicitly constant (for example, you
        can't re-assign a reference). Remember also that "const T &amp;"
        is something completely different. For this reason, cv-qualifiers on template
        type arguments that are references are ignored.
      </listitem>
    </orderedlist>
  </section>
  <section id="boost_typetraits.category">
    <title><link linkend="boost_typetraits.category"> Type Traits by Category</link></title>
    <section id="boost_typetraits.category.value_traits">
      <title><link linkend="boost_typetraits.category.value_traits"> Type Traits
      that Describe the Properties of a Type</link></title>
      <para>
        <indexterm>
          <primary>Foo2</primary>
          <secondary>Bar2</secondary>
        </indexterm>
        These traits are all <emphasis>value traits</emphasis>, which is to say the
        traits classes all inherit from <link linkend="boost_typetraits.reference.integral_constant">integral_constant</link>,
        and are used to access some numerical property of a type. Often this is a
        simple true or false Boolean value, but in a few cases may be some other
        integer value (for example when dealing with type alignments, or array bounds:
        see <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.alignment_of">alignment_of</link></computeroutput>,
        <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.rank">rank</link></computeroutput>
        and <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.extent">extent</link></computeroutput>).
      </para>
      <section id="boost_typetraits.category.value_traits.primary">
        <title><link linkend="boost_typetraits.category.value_traits.primary"> Categorizing
        a Type</link></title>
        <para>
          These traits identify what "kind" of type some type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput> is. These are split into two groups:
          primary traits which are all mutually exclusive, and composite traits that
          are compositions of one or more primary traits.
        </para>
        <para>
          For any given type, exactly one primary type trait will inherit from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
          and all the others will inherit from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>,
          in other words these traits are mutually exclusive.
        </para>
        <para>
          This means that <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.is_integral">is_integral</link><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput>
          and <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.is_floating_point">is_floating_point</link><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput>
          will only ever be true for built-in types; if you want to check for a user-defined
          class type that behaves "as if" it is an integral or floating
          point type, then use the <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">numeric_limits</phrase>
          <phrase role="keyword">template</phrase></computeroutput> instead.
        </para>
        <para>
          <emphasis role="bold">Synopsis:</emphasis>
        </para>
        
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_array">is_array</link><phrase role="special">;</phrase>
  
<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_class">is_class</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_complex">is_complex</link><phrase role="special">;</phrase>
  
<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_enum">is_enum</link><phrase role="special">;</phrase>
  
<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_floating_point">is_floating_point</link><phrase role="special">;</phrase>
  
<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_function">is_function</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_integral">is_integral</link><phrase role="special">;</phrase>
  
<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_member_function_pointer">is_member_function_pointer</link><phrase role="special">;</phrase>
  
<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_member_object_pointer">is_member_object_pointer</link><phrase role="special">;</phrase>
  
<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_pointer">is_pointer</link><phrase role="special">;</phrase>
  
<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_reference">is_reference</link><phrase role="special">;</phrase>
  
<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_union">is_union</link><phrase role="special">;</phrase>
  
<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_void">is_void</link><phrase role="special">;</phrase>
</programlisting>
        <para>
          The following traits are made up of the union of one or more type categorizations.
          A type may belong to more than one of these categories, in addition to
          one of the primary categories.
        </para>
        
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_arithmetic">is_arithmetic</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_compound">is_compound</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_fundamental">is_fundamental</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_member_pointer">is_member_pointer</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_object">is_object</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_scalar">is_scalar</link><phrase role="special">;</phrase>
</programlisting>
      </section>
      <section id="boost_typetraits.category.value_traits.properties">
        <title><link linkend="boost_typetraits.category.value_traits.properties">
        General Type Properties</link></title>
        <para>
          The following templates describe the general properties of a type.
        </para>
        <para>
          <emphasis role="bold">Synopsis:</emphasis>
        </para>
        
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.alignment_of">alignment_of</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.has_nothrow_assign">has_nothrow_assign</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.has_nothrow_constructor">has_nothrow_constructor</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.has_nothrow_constructor">has_nothrow_default_constructor</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.has_nothrow_copy">has_nothrow_copy</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.has_nothrow_copy">has_nothrow_copy_constructor</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.has_trivial_assign">has_trivial_assign</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.has_trivial_constructor">has_trivial_constructor</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.has_trivial_constructor">has_trivial_default_constructor</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.has_trivial_copy">has_trivial_copy</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.has_trivial_copy">has_trivial_copy_constructor</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.has_trivial_destructor">has_trivial_destructor</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.has_virtual_destructor">has_virtual_destructor</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_abstract">is_abstract</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_const">is_const</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_empty">is_empty</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_stateless">is_stateless</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_pod">is_pod</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_polymorphic">is_polymorphic</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_signed">is_signed</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_unsigned">is_unsigned</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_volatile">is_volatile</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">,</phrase> <phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">size_t</phrase> <phrase role="identifier">N</phrase> <phrase role="special">=</phrase> <phrase role="number">0</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.extent">extent</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.rank">rank</link><phrase role="special">;</phrase>
</programlisting>
      </section>
      <section id="boost_typetraits.category.value_traits.relate">
        <title><link linkend="boost_typetraits.category.value_traits.relate"> Relationships
        Between Two Types</link></title>
        <para>
          These templates determine the whether there is a relationship between two
          types:
        </para>
        <para>
          <emphasis role="bold">Synopsis:</emphasis>
        </para>
        
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">Base</phrase><phrase role="special">,</phrase> <phrase role="keyword">class</phrase> <phrase role="identifier">Derived</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_base_of">is_base_of</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">From</phrase><phrase role="special">,</phrase> <phrase role="keyword">class</phrase> <phrase role="identifier">To</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_convertible">is_convertible</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">,</phrase> <phrase role="keyword">class</phrase> <phrase role="identifier">U</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_same">is_same</link><phrase role="special">;</phrase>
</programlisting>
      </section>
    </section>
    <section id="boost_typetraits.category.transform"><indexterm type="macro_name"><primary>BOOST_BROKEN_COMPILER_TYPE_TRAITS_SPECIALIZATION</primary><secondary>Type Traits that Transform One Type to Another</secondary></indexterm><indexterm><primary>Type Traits that Transform One Type to Another</primary><secondary>BOOST_BROKEN_COMPILER_TYPE_TRAITS_SPECIALIZATION</secondary></indexterm><indexterm type="macro_name"><primary>BOOST_BROKEN_COMPILER_TYPE_TRAITS_SPECIALIZATION</primary><secondary>Type Traits that Transform One Type to Another</secondary></indexterm><indexterm><primary>Type Traits that Transform One Type to Another</primary><secondary>BOOST_BROKEN_COMPILER_TYPE_TRAITS_SPECIALIZATION</secondary></indexterm>
      <title><link linkend="boost_typetraits.category.transform"> Type Traits that
      Transform One Type to Another</link></title>
      <para>
        The following templates transform one type to another, based upon some well-defined
        rule. Each template has a single member called <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">type</phrase></computeroutput>
        that is the result of applying the transformation to the template argument
        <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>.
      </para>
      <para>
        <emphasis role="bold">Synopsis:</emphasis>
      </para>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.add_const">add_const</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.add_cv">add_cv</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.add_pointer">add_pointer</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.add_reference">add_reference</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.add_volatile">add_volatile</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.decay">decay</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.floating_point_promotion">floating_point_promotion</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.integral_promotion">integral_promotion</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.make_signed">make_signed</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.make_unsigned">make_unsigned</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.promote">promote</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.remove_all_extents">remove_all_extents</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.remove_const">remove_const</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.remove_cv">remove_cv</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.remove_extent">remove_extent</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.remove_pointer">remove_pointer</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.remove_reference">remove_reference</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.remove_volatile">remove_volatile</link><phrase role="special">;</phrase>
</programlisting>
      <anchor id="boost_typetraits.category.transform.broken_compiler_workarounds_"/>
      <bridgehead renderas="sect4">
        <link linkend="boost_typetraits.category.transform.broken_compiler_workarounds_">Broken
        Compiler Workarounds:</link>
      </bridgehead>
      <para>
        For all of these templates support for partial specialization of class templates
        is required to correctly implement the transformation. On the other hand,
        practice shows that many of the templates from this category are very useful,
        and often essential for implementing some generic libraries. Lack of these
        templates is often one of the major limiting factors in porting those libraries
        to compilers that do not yet support this language feature. As some of these
        compilers are going to be around for a while, and at least one of them is
        very wide-spread, it was decided that the library should provide workarounds
        where possible.
      </para>
      <para>
        The basic idea behind the workaround is to manually define full specializations
        of all type transformation templates for all fundamental types, and all their
        1st and 2nd rank cv-[un]qualified derivative pointer types, and to provide
        a user-level macro that will define all the explicit specializations needed
        for any user-defined type T.
      </para>
      <para>
        The first part guarantees the successful compilation of something like this:
      </para>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">BOOST_STATIC_ASSERT</phrase><phrase role="special">((</phrase><phrase role="identifier">is_same</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">char</phrase><phrase role="special">,</phrase> <phrase role="identifier">remove_reference</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">char</phrase><phrase role="special">&amp;&gt;::</phrase><phrase role="identifier">type</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase><phrase role="special">));</phrase>
<phrase role="identifier">BOOST_STATIC_ASSERT</phrase><phrase role="special">((</phrase><phrase role="identifier">is_same</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">char</phrase> <phrase role="keyword">const</phrase><phrase role="special">,</phrase> <phrase role="identifier">remove_reference</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">char</phrase> <phrase role="keyword">const</phrase><phrase role="special">&amp;&gt;::</phrase><phrase role="identifier">type</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase><phrase role="special">));</phrase>
<phrase role="identifier">BOOST_STATIC_ASSERT</phrase><phrase role="special">((</phrase><phrase role="identifier">is_same</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">char</phrase> <phrase role="keyword">volatile</phrase><phrase role="special">,</phrase> <phrase role="identifier">remove_reference</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">char</phrase> <phrase role="keyword">volatile</phrase><phrase role="special">&amp;&gt;::</phrase><phrase role="identifier">type</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase><phrase role="special">));</phrase>
<phrase role="identifier">BOOST_STATIC_ASSERT</phrase><phrase role="special">((</phrase><phrase role="identifier">is_same</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">char</phrase> <phrase role="keyword">const</phrase> <phrase role="keyword">volatile</phrase><phrase role="special">,</phrase> <phrase role="identifier">remove_reference</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">char</phrase> <phrase role="keyword">const</phrase> <phrase role="keyword">volatile</phrase><phrase role="special">&amp;&gt;::</phrase><phrase role="identifier">type</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase><phrase role="special">));</phrase>
<phrase role="identifier">BOOST_STATIC_ASSERT</phrase><phrase role="special">((</phrase><phrase role="identifier">is_same</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">char</phrase><phrase role="special">*,</phrase> <phrase role="identifier">remove_reference</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">char</phrase><phrase role="special">*&amp;&gt;::</phrase><phrase role="identifier">type</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase><phrase role="special">));</phrase>
<phrase role="identifier">BOOST_STATIC_ASSERT</phrase><phrase role="special">((</phrase><phrase role="identifier">is_same</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">char</phrase> <phrase role="keyword">const</phrase><phrase role="special">*,</phrase> <phrase role="identifier">remove_reference</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">char</phrase> <phrase role="keyword">const</phrase><phrase role="special">*&amp;&gt;::</phrase><phrase role="identifier">type</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase><phrase role="special">));</phrase>
<phrase role="special">...</phrase>
<phrase role="identifier">BOOST_STATIC_ASSERT</phrase><phrase role="special">((</phrase><phrase role="identifier">is_same</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">char</phrase> <phrase role="keyword">const</phrase> <phrase role="keyword">volatile</phrase><phrase role="special">*</phrase> <phrase role="keyword">const</phrase> <phrase role="keyword">volatile</phrase><phrase role="special">*</phrase> <phrase role="keyword">const</phrase> <phrase role="keyword">volatile</phrase><phrase role="special">,</phrase> <phrase role="identifier">remove_reference</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">char</phrase> <phrase role="keyword">const</phrase> <phrase role="keyword">volatile</phrase><phrase role="special">*</phrase> <phrase role="keyword">const</phrase> <phrase role="keyword">volatile</phrase><phrase role="special">*</phrase> <phrase role="keyword">const</phrase> <phrase role="keyword">volatile</phrase><phrase role="special">&amp;&gt;::</phrase><phrase role="identifier">type</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase><phrase role="special">));</phrase>
</programlisting>
      <para>
        and the second part provides the library's users with a mechanism to make
        the above code work not only for <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">char</phrase></computeroutput>,
        <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase></computeroutput> or other built-in type,
        but for their own types as well:
      </para>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">namespace</phrase> <phrase role="identifier">myspace</phrase><phrase role="special">{</phrase>
   <phrase role="keyword">struct</phrase> <phrase role="identifier">MyClass</phrase> <phrase role="special">{};</phrase>
<phrase role="special">}</phrase>
<phrase role="comment">// declare this at global scope:
</phrase><phrase role="identifier">BOOST_BROKEN_COMPILER_TYPE_TRAITS_SPECIALIZATION</phrase><phrase role="special">(</phrase><phrase role="identifier">myspace</phrase><phrase role="special">::</phrase><phrase role="identifier">MyClass</phrase><phrase role="special">)</phrase>
<phrase role="comment">// transformations on myspace::MyClass now work:
</phrase><phrase role="identifier">BOOST_STATIC_ASSERT</phrase><phrase role="special">((</phrase><phrase role="identifier">is_same</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">myspace</phrase><phrase role="special">::</phrase><phrase role="identifier">MyClass</phrase><phrase role="special">,</phrase> <phrase role="identifier">remove_reference</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">myspace</phrase><phrase role="special">::</phrase><phrase role="identifier">MyClass</phrase><phrase role="special">&amp;&gt;::</phrase><phrase role="identifier">type</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase><phrase role="special">));</phrase>
<phrase role="identifier">BOOST_STATIC_ASSERT</phrase><phrase role="special">((</phrase><phrase role="identifier">is_same</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">myspace</phrase><phrase role="special">::</phrase><phrase role="identifier">MyClass</phrase><phrase role="special">,</phrase> <phrase role="identifier">remove_const</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">myspace</phrase><phrase role="special">::</phrase><phrase role="identifier">MyClass</phrase> <phrase role="keyword">const</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase><phrase role="special">));</phrase>
<phrase role="comment">// etc.
</phrase></programlisting>
      <para>
        Note that the macro BOOST_BROKEN_COMPILER_TYPE_TRAITS_SPECIALIZATION evaluates
        to nothing on those compilers that <emphasis role="bold">do</emphasis> support
        partial specialization.
      </para>
    </section>
    <section id="boost_typetraits.category.alignment">
      <title><link linkend="boost_typetraits.category.alignment"> Synthesizing Types
      with Specific Alignments</link></title>
      <para>
        Some low level memory management routines need to synthesize a POD type with
        specific alignment properties. The template <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.type_with_alignment">type_with_alignment</link></computeroutput>
        finds the smallest type with a specified alignment, while template <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.aligned_storage">aligned_storage</link></computeroutput>
        creates a type with a specific size and alignment.
      </para>
      <para>
        <emphasis role="bold">Synopsis</emphasis>
      </para>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">size_t</phrase> <phrase role="identifier">Align</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.type_with_alignment">type_with_alignment</link><phrase role="special">;</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">size_t</phrase> <phrase role="identifier">Size</phrase><phrase role="special">,</phrase> <phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">size_t</phrase> <phrase role="identifier">Align</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.aligned_storage">aligned_storage</link><phrase role="special">;</phrase>
</programlisting>
    </section>
    <section id="boost_typetraits.category.function">
      <title><link linkend="boost_typetraits.category.function"> Decomposing Function
      Types</link></title>
      <para>
        The class template <link linkend="boost_typetraits.reference.function_traits">function_traits</link>
        extracts information from function types (see also <link linkend="boost_typetraits.reference.is_function">is_function</link>).
        This traits class allows you to tell how many arguments a function takes,
        what those argument types are, and what the return type is.
      </para>
      <para>
        <emphasis role="bold">Synopsis</emphasis>
      </para>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">size_t</phrase> <phrase role="identifier">Align</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.function_traits">function_traits</link><phrase role="special">;</phrase>
</programlisting>
    </section>
  </section>
  <section id="boost_typetraits.user_defined"><indexterm type="class_name"><primary>is_union</primary><secondary>User Defined Specializations</secondary></indexterm><indexterm><primary>User Defined Specializations</primary><secondary>is_union</secondary></indexterm><indexterm type="class_name"><primary>is_class</primary><secondary>User Defined Specializations</secondary></indexterm><indexterm><primary>User Defined Specializations</primary><secondary>is_class</secondary></indexterm>
    <title><link linkend="boost_typetraits.user_defined"> User Defined Specializations</link></title>
    <para>
      Occationally the end user may need to provide their own specialization for
      one of the type traits - typically where intrinsic compiler support is required
      to implement a specific trait fully. These specializations should derive from
      boost::<link linkend="boost_typetraits.reference.integral_constant">true_type</link>
      or boost::<link linkend="boost_typetraits.reference.integral_constant">false_type</link>
      as appropriate:
    </para>
    
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">is_pod</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase>
<phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">is_class</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase>
<phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">is_union</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase>

<phrase role="keyword">struct</phrase> <phrase role="identifier">my_pod</phrase><phrase role="special">{};</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">my_union</phrase>
<phrase role="special">{</phrase>
   <phrase role="keyword">char</phrase> <phrase role="identifier">c</phrase><phrase role="special">;</phrase>
   <phrase role="keyword">int</phrase> <phrase role="identifier">i</phrase><phrase role="special">;</phrase>
<phrase role="special">};</phrase>

<phrase role="keyword">namespace</phrase> <phrase role="identifier">boost</phrase>
<phrase role="special">{</phrase>
   <phrase role="keyword">template</phrase><phrase role="special">&lt;&gt;</phrase>
   <phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_pod">is_pod</link><phrase role="special">&lt;</phrase><phrase role="identifier">my_pod</phrase><phrase role="special">&gt;</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <link linkend="boost_typetraits.reference.integral_constant">true_type</link><phrase role="special">{};</phrase>
      
   <phrase role="keyword">template</phrase><phrase role="special">&lt;&gt;</phrase>
   <phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_pod">is_pod</link><phrase role="special">&lt;</phrase><phrase role="identifier">my_union</phrase><phrase role="special">&gt;</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <link linkend="boost_typetraits.reference.integral_constant">true_type</link><phrase role="special">{};</phrase>
   
   <phrase role="keyword">template</phrase><phrase role="special">&lt;&gt;</phrase>
   <phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_union">is_union</link><phrase role="special">&lt;</phrase><phrase role="identifier">my_union</phrase><phrase role="special">&gt;</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <link linkend="boost_typetraits.reference.integral_constant">true_type</link><phrase role="special">{};</phrase>
   
   <phrase role="keyword">template</phrase><phrase role="special">&lt;&gt;</phrase>
   <phrase role="keyword">struct</phrase> <link linkend="boost_typetraits.reference.is_class">is_class</link><phrase role="special">&lt;</phrase><phrase role="identifier">my_union</phrase><phrase role="special">&gt;</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <link linkend="boost_typetraits.reference.integral_constant">false_type</link><phrase role="special">{};</phrase>
<phrase role="special">}</phrase>
</programlisting>
  </section>
  <section id="boost_typetraits.intrinsics"><indexterm type="macro_name"><primary>BOOST_IS_UNION</primary><secondary>Support for Compiler Intrinsics</secondary></indexterm><indexterm><primary>Support for Compiler Intrinsics</primary><secondary>BOOST_IS_UNION</secondary></indexterm><indexterm type="macro_name"><primary>BOOST_IS_POLYMORPHIC</primary><secondary>Support for Compiler Intrinsics</secondary></indexterm><indexterm><primary>Support for Compiler Intrinsics</primary><secondary>BOOST_IS_POLYMORPHIC</secondary></indexterm><indexterm type="macro_name"><primary>BOOST_IS_POD</primary><secondary>Support for Compiler Intrinsics</secondary></indexterm><indexterm><primary>Support for Compiler Intrinsics</primary><secondary>BOOST_IS_POD</secondary></indexterm><indexterm type="macro_name"><primary>BOOST_IS_ENUM</primary><secondary>Support for Compiler Intrinsics</secondary></indexterm><indexterm><primary>Support for Compiler Intrinsics</primary><secondary>BOOST_IS_ENUM</secondary></indexterm><indexterm type="macro_name"><primary>BOOST_IS_EMPTY</primary><secondary>Support for Compiler Intrinsics</secondary></indexterm><indexterm><primary>Support for Compiler Intrinsics</primary><secondary>BOOST_IS_EMPTY</secondary></indexterm><indexterm type="macro_name"><primary>BOOST_IS_CONVERTIBLE</primary><secondary>Support for Compiler Intrinsics</secondary></indexterm><indexterm><primary>Support for Compiler Intrinsics</primary><secondary>BOOST_IS_CONVERTIBLE</secondary></indexterm><indexterm type="macro_name"><primary>BOOST_IS_CLASS</primary><secondary>Support for Compiler Intrinsics</secondary></indexterm><indexterm><primary>Support for Compiler Intrinsics</primary><secondary>BOOST_IS_CLASS</secondary></indexterm><indexterm type="macro_name"><primary>BOOST_IS_BASE_OF</primary><secondary>Support for Compiler Intrinsics</secondary></indexterm><indexterm><primary>Support for Compiler Intrinsics</primary><secondary>BOOST_IS_BASE_OF</secondary></indexterm><indexterm type="macro_name"><primary>BOOST_IS_ABSTRACT</primary><secondary>Support for Compiler Intrinsics</secondary></indexterm><indexterm><primary>Support for Compiler Intrinsics</primary><secondary>BOOST_IS_ABSTRACT</secondary></indexterm><indexterm type="macro_name"><primary>BOOST_HAS_VIRTUAL_DESTRUCTOR</primary><secondary>Support for Compiler Intrinsics</secondary></indexterm><indexterm><primary>Support for Compiler Intrinsics</primary><secondary>BOOST_HAS_VIRTUAL_DESTRUCTOR</secondary></indexterm><indexterm type="macro_name"><primary>BOOST_HAS_TRIVIAL_DESTRUCTOR</primary><secondary>Support for Compiler Intrinsics</secondary></indexterm><indexterm><primary>Support for Compiler Intrinsics</primary><secondary>BOOST_HAS_TRIVIAL_DESTRUCTOR</secondary></indexterm><indexterm type="macro_name"><primary>BOOST_HAS_TRIVIAL_COPY</primary><secondary>Support for Compiler Intrinsics</secondary></indexterm><indexterm><primary>Support for Compiler Intrinsics</primary><secondary>BOOST_HAS_TRIVIAL_COPY</secondary></indexterm><indexterm type="macro_name"><primary>BOOST_HAS_TRIVIAL_CONSTRUCTOR</primary><secondary>Support for Compiler Intrinsics</secondary></indexterm><indexterm><primary>Support for Compiler Intrinsics</primary><secondary>BOOST_HAS_TRIVIAL_CONSTRUCTOR</secondary></indexterm><indexterm type="macro_name"><primary>BOOST_HAS_TRIVIAL_ASSIGN</primary><secondary>Support for Compiler Intrinsics</secondary></indexterm><indexterm><primary>Support for Compiler Intrinsics</primary><secondary>BOOST_HAS_TRIVIAL_ASSIGN</secondary></indexterm><indexterm type="macro_name"><primary>BOOST_HAS_NOTHROW_COPY</primary><secondary>Support for Compiler Intrinsics</secondary></indexterm><indexterm><primary>Support for Compiler Intrinsics</primary><secondary>BOOST_HAS_NOTHROW_COPY</secondary></indexterm><indexterm type="macro_name"><primary>BOOST_HAS_NOTHROW_CONSTRUCTOR</primary><secondary>Support for Compiler Intrinsics</secondary></indexterm><indexterm><primary>Support for Compiler Intrinsics</primary><secondary>BOOST_HAS_NOTHROW_CONSTRUCTOR</secondary></indexterm><indexterm type="macro_name"><primary>BOOST_HAS_NOTHROW_ASSIGN</primary><secondary>Support for Compiler Intrinsics</secondary></indexterm><indexterm><primary>Support for Compiler Intrinsics</primary><secondary>BOOST_HAS_NOTHROW_ASSIGN</secondary></indexterm><indexterm type="macro_name"><primary>BOOST_ALIGNMENT_OF</primary><secondary>Support for Compiler Intrinsics</secondary></indexterm><indexterm><primary>Support for Compiler Intrinsics</primary><secondary>BOOST_ALIGNMENT_OF</secondary></indexterm>
    <title><link linkend="boost_typetraits.intrinsics"> Support for Compiler Intrinsics</link></title>
    <para>
      There are some traits that can not be implemented within the current C++ language:
      to make these traits "just work" with user defined types, some kind
      of additional help from the compiler is required. Currently (April 2008) Visual
      C++ 8 and 9, GNU GCC 4.3 and MWCW 9 provide the necessary intrinsics, and other
      compilers will no doubt follow in due course.
    </para>
    <para>
      The Following traits classes always need compiler support to do the right thing
      for all types (but all have safe fallback positions if this support is unavailable):
    </para>
    <itemizedlist>
      <listitem>
        <link linkend="boost_typetraits.reference.is_union">is_union</link>
      </listitem>
      <listitem>
        <link linkend="boost_typetraits.reference.is_pod">is_pod</link>
      </listitem>
      <listitem>
        <link linkend="boost_typetraits.reference.has_trivial_constructor">has_trivial_constructor</link>
      </listitem>
      <listitem>
        <link linkend="boost_typetraits.reference.has_trivial_copy">has_trivial_copy</link>
      </listitem>
      <listitem>
        <link linkend="boost_typetraits.reference.has_trivial_assign">has_trivial_assign</link>
      </listitem>
      <listitem>
        <link linkend="boost_typetraits.reference.has_trivial_destructor">has_trivial_destructor</link>
      </listitem>
      <listitem>
        <link linkend="boost_typetraits.reference.has_nothrow_constructor">has_nothrow_constructor</link>
      </listitem>
      <listitem>
        <link linkend="boost_typetraits.reference.has_nothrow_copy">has_nothrow_copy</link>
      </listitem>
      <listitem>
        <link linkend="boost_typetraits.reference.has_nothrow_assign">has_nothrow_assign</link>
      </listitem>
      <listitem>
        <link linkend="boost_typetraits.reference.has_virtual_destructor">has_virtual_destructor</link>
      </listitem>
    </itemizedlist>
    <para>
      The following traits classes can't be portably implemented in the C++ language,
      although in practice, the implementations do in fact do the right thing on
      all the compilers we know about:
    </para>
    <itemizedlist>
      <listitem>
        <link linkend="boost_typetraits.reference.is_empty">is_empty</link>
      </listitem>
      <listitem>
        <link linkend="boost_typetraits.reference.is_polymorphic">is_polymorphic</link>
      </listitem>
    </itemizedlist>
    <para>
      The following traits classes are dependent on one or more of the above:
    </para>
    <itemizedlist>
      <listitem>
        <link linkend="boost_typetraits.reference.is_class">is_class</link>
      </listitem>
      <listitem>
        <link linkend="boost_typetraits.reference.is_stateless">is_stateless</link>
      </listitem>
    </itemizedlist>
    <para>
      The hooks for compiler-intrinsic support are defined in <ulink url="../../../../boost/type_traits/intrinsics.hpp">boost/type_traits/intrinsics.hpp</ulink>,
      adding support for new compilers is simply a matter of defining one of more
      of the following macros:
    </para>
    <table frame="all"> <title>Macros for Compiler Intrinsics</title>
    <tgroup cols="2">
      <thead>
        <row>
          <entry>
          <para>
            BOOST_IS_UNION(T)
          </para>
          </entry><entry>
          <para>
            Should evaluate to true if T is a union type
          </para>
          </entry>
        </row>
      </thead>
      <tbody>
        <row>
          <entry>
          <para>
            BOOST_IS_POD(T)
          </para>
          </entry><entry>
          <para>
            Should evaluate to true if T is a POD type
          </para>
          </entry>
        </row>
        <row>
          <entry>
          <para>
            BOOST_IS_EMPTY(T)
          </para>
          </entry><entry>
          <para>
            Should evaluate to true if T is an empty struct or union
          </para>
          </entry>
        </row>
        <row>
          <entry>
          <para>
            BOOST_HAS_TRIVIAL_CONSTRUCTOR(T)
          </para>
          </entry><entry>
          <para>
            Should evaluate to true if the default constructor for T is trivial (i.e.
            has no effect)
          </para>
          </entry>
        </row>
        <row>
          <entry>
          <para>
            BOOST_HAS_TRIVIAL_COPY(T)
          </para>
          </entry><entry>
          <para>
            Should evaluate to true if T has a trivial copy constructor (and can
            therefore be replaced by a call to memcpy)
          </para>
          </entry>
        </row>
        <row>
          <entry>
          <para>
            BOOST_HAS_TRIVIAL_ASSIGN(T)
          </para>
          </entry><entry>
          <para>
            Should evaluate to true if T has a trivial assignment operator (and can
            therefore be replaced by a call to memcpy)
          </para>
          </entry>
        </row>
        <row>
          <entry>
          <para>
            BOOST_HAS_TRIVIAL_DESTRUCTOR(T)
          </para>
          </entry><entry>
          <para>
            Should evaluate to true if T has a trivial destructor (i.e. ~T() has
            no effect)
          </para>
          </entry>
        </row>
        <row>
          <entry>
          <para>
            BOOST_HAS_NOTHROW_CONSTRUCTOR(T)
          </para>
          </entry><entry>
          <para>
            Should evaluate to true if <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase>
            <phrase role="identifier">x</phrase><phrase role="special">;</phrase></computeroutput>
            can not throw
          </para>
          </entry>
        </row>
        <row>
          <entry>
          <para>
            BOOST_HAS_NOTHROW_COPY(T)
          </para>
          </entry><entry>
          <para>
            Should evaluate to true if <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase><phrase role="special">(</phrase><phrase role="identifier">t</phrase><phrase role="special">)</phrase></computeroutput> can not throw
          </para>
          </entry>
        </row>
        <row>
          <entry>
          <para>
            BOOST_HAS_NOTHROW_ASSIGN(T)
          </para>
          </entry><entry>
          <para>
            Should evaluate to true if <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase>
            <phrase role="identifier">t</phrase><phrase role="special">,</phrase>
            <phrase role="identifier">u</phrase><phrase role="special">;</phrase>
            <phrase role="identifier">t</phrase> <phrase role="special">=</phrase>
            <phrase role="identifier">u</phrase></computeroutput> can not throw
          </para>
          </entry>
        </row>
        <row>
          <entry>
          <para>
            BOOST_HAS_VIRTUAL_DESTRUCTOR(T)
          </para>
          </entry><entry>
          <para>
            Should evaluate to true T has a virtual destructor
          </para>
          </entry>
        </row>
        <row>
          <entry>
          <para>
            BOOST_IS_ABSTRACT(T)
          </para>
          </entry><entry>
          <para>
            Should evaluate to true if T is an abstract type
          </para>
          </entry>
        </row>
        <row>
          <entry>
          <para>
            BOOST_IS_BASE_OF(T,U)
          </para>
          </entry><entry>
          <para>
            Should evaluate to true if T is a base class of U
          </para>
          </entry>
        </row>
        <row>
          <entry>
          <para>
            BOOST_IS_CLASS(T)
          </para>
          </entry><entry>
          <para>
            Should evaluate to true if T is a class type
          </para>
          </entry>
        </row>
        <row>
          <entry>
          <para>
            BOOST_IS_CONVERTIBLE(T,U)
          </para>
          </entry><entry>
          <para>
            Should evaluate to true if T is convertible to U
          </para>
          </entry>
        </row>
        <row>
          <entry>
          <para>
            BOOST_IS_ENUM(T)
          </para>
          </entry><entry>
          <para>
            Should evaluate to true is T is an enum
          </para>
          </entry>
        </row>
        <row>
          <entry>
          <para>
            BOOST_IS_POLYMORPHIC(T)
          </para>
          </entry><entry>
          <para>
            Should evaluate to true if T is a polymorphic type
          </para>
          </entry>
        </row>
        <row>
          <entry>
          <para>
            BOOST_ALIGNMENT_OF(T)
          </para>
          </entry><entry>
          <para>
            Should evaluate to the alignment requirements of type T.
          </para>
          </entry>
        </row>
      </tbody>
    </tgroup>
    </table>
  </section>
  <section id="boost_typetraits.mpl">
    <title><link linkend="boost_typetraits.mpl"> MPL Interoperability</link></title>
    <para>
      All the value based traits in this library conform to MPL's requirements for
      an <ulink url="../../../../libs/mpl/doc/refmanual/integral-constant.html">Integral
      Constant type</ulink>: that includes a number of rather intrusive workarounds
      for broken compilers.
    </para>
    <para>
      Purely as an implementation detail, this means that <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>
      inherits from <ulink url="../../../../libs/mpl/doc/refmanual/bool.html"><computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">boost</phrase><phrase role="special">::</phrase><phrase role="identifier">mpl</phrase><phrase role="special">::</phrase><phrase role="identifier">true_</phrase></computeroutput></ulink>,
      <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">false_type</link></computeroutput>
      inherits from <ulink url="../../../../libs/mpl/doc/refmanual/bool.html"><computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">boost</phrase><phrase role="special">::</phrase><phrase role="identifier">mpl</phrase><phrase role="special">::</phrase><phrase role="identifier">false_</phrase></computeroutput></ulink>,
      and <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">integral_constant</link><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">,</phrase>
      <phrase role="identifier">v</phrase><phrase role="special">&gt;</phrase></computeroutput>
      inherits from <ulink url="../../../../libs/mpl/doc/refmanual/integral-c.html"><computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">boost</phrase><phrase role="special">::</phrase><phrase role="identifier">mpl</phrase><phrase role="special">::</phrase><phrase role="identifier">integral_c</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">,</phrase><phrase role="identifier">v</phrase><phrase role="special">&gt;</phrase></computeroutput></ulink>
      (provided <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput> is not <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">bool</phrase></computeroutput>)
    </para>
  </section>
  <section id="boost_typetraits.examples">
    <title><link linkend="boost_typetraits.examples"> Examples</link></title>
    <section id="boost_typetraits.examples.copy"><indexterm type="typedef_name"><primary>value_type</primary><secondary>An Optimized Version of std::copy</secondary></indexterm><indexterm><primary>Optimized Version of std::copy</primary><secondary>value_type</secondary></indexterm>
      <title><link linkend="boost_typetraits.examples.copy"> An Optimized Version
      of std::copy</link></title>
      <para>
        Demonstrates a version of <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">copy</phrase></computeroutput>
        that uses <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.has_trivial_assign">has_trivial_assign</link></computeroutput>
        to determine whether to use <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">memcpy</phrase></computeroutput>
        to optimise the copy operation (see <ulink url="../../examples/copy_example.cpp">copy_example.cpp</ulink>):
      </para>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="comment">//
</phrase><phrase role="comment">// opt::copy
</phrase><phrase role="comment">// same semantics as std::copy
</phrase><phrase role="comment">// calls memcpy where appropriate.
</phrase><phrase role="comment">//
</phrase>
<phrase role="keyword">namespace</phrase> <phrase role="identifier">detail</phrase><phrase role="special">{</phrase>

<phrase role="keyword">template</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">typename</phrase> <phrase role="identifier">I1</phrase><phrase role="special">,</phrase> <phrase role="keyword">typename</phrase> <phrase role="identifier">I2</phrase><phrase role="special">,</phrase> <phrase role="keyword">bool</phrase> <phrase role="identifier">b</phrase><phrase role="special">&gt;</phrase>
<phrase role="identifier">I2</phrase> <phrase role="identifier">copy_imp</phrase><phrase role="special">(</phrase><phrase role="identifier">I1</phrase> <phrase role="identifier">first</phrase><phrase role="special">,</phrase> <phrase role="identifier">I1</phrase> <phrase role="identifier">last</phrase><phrase role="special">,</phrase> <phrase role="identifier">I2</phrase> <phrase role="identifier">out</phrase><phrase role="special">,</phrase> <phrase role="keyword">const</phrase> <phrase role="identifier">boost</phrase><phrase role="special">::</phrase><link linkend="boost_typetraits.reference.integral_constant">integral_constant</link><phrase role="special">&lt;</phrase><phrase role="keyword">bool</phrase><phrase role="special">,</phrase> <phrase role="identifier">b</phrase><phrase role="special">&gt;&amp;)</phrase>
<phrase role="special">{</phrase>
   <phrase role="keyword">while</phrase><phrase role="special">(</phrase><phrase role="identifier">first</phrase> <phrase role="special">!=</phrase> <phrase role="identifier">last</phrase><phrase role="special">)</phrase>
   <phrase role="special">{</phrase>
      <phrase role="special">*</phrase><phrase role="identifier">out</phrase> <phrase role="special">=</phrase> <phrase role="special">*</phrase><phrase role="identifier">first</phrase><phrase role="special">;</phrase>
      <phrase role="special">++</phrase><phrase role="identifier">out</phrase><phrase role="special">;</phrase>
      <phrase role="special">++</phrase><phrase role="identifier">first</phrase><phrase role="special">;</phrase>
   <phrase role="special">}</phrase>
   <phrase role="keyword">return</phrase> <phrase role="identifier">out</phrase><phrase role="special">;</phrase>
<phrase role="special">}</phrase>

<phrase role="keyword">template</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">typename</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="identifier">T</phrase><phrase role="special">*</phrase> <phrase role="identifier">copy_imp</phrase><phrase role="special">(</phrase><phrase role="keyword">const</phrase> <phrase role="identifier">T</phrase><phrase role="special">*</phrase> <phrase role="identifier">first</phrase><phrase role="special">,</phrase> <phrase role="keyword">const</phrase> <phrase role="identifier">T</phrase><phrase role="special">*</phrase> <phrase role="identifier">last</phrase><phrase role="special">,</phrase> <phrase role="identifier">T</phrase><phrase role="special">*</phrase> <phrase role="identifier">out</phrase><phrase role="special">,</phrase> <phrase role="keyword">const</phrase> <phrase role="identifier">boost</phrase><phrase role="special">::</phrase><link linkend="boost_typetraits.reference.integral_constant">true_type</link><phrase role="special">&amp;)</phrase>
<phrase role="special">{</phrase>
   <phrase role="identifier">memcpy</phrase><phrase role="special">(</phrase><phrase role="identifier">out</phrase><phrase role="special">,</phrase> <phrase role="identifier">first</phrase><phrase role="special">,</phrase> <phrase role="special">(</phrase><phrase role="identifier">last</phrase><phrase role="special">-</phrase><phrase role="identifier">first</phrase><phrase role="special">)*</phrase><phrase role="keyword">sizeof</phrase><phrase role="special">(</phrase><phrase role="identifier">T</phrase><phrase role="special">));</phrase>
   <phrase role="keyword">return</phrase> <phrase role="identifier">out</phrase><phrase role="special">+(</phrase><phrase role="identifier">last</phrase><phrase role="special">-</phrase><phrase role="identifier">first</phrase><phrase role="special">);</phrase>
<phrase role="special">}</phrase>


<phrase role="special">}</phrase>

<phrase role="keyword">template</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">typename</phrase> <phrase role="identifier">I1</phrase><phrase role="special">,</phrase> <phrase role="keyword">typename</phrase> <phrase role="identifier">I2</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">inline</phrase> <phrase role="identifier">I2</phrase> <phrase role="identifier">copy</phrase><phrase role="special">(</phrase><phrase role="identifier">I1</phrase> <phrase role="identifier">first</phrase><phrase role="special">,</phrase> <phrase role="identifier">I1</phrase> <phrase role="identifier">last</phrase><phrase role="special">,</phrase> <phrase role="identifier">I2</phrase> <phrase role="identifier">out</phrase><phrase role="special">)</phrase>
<phrase role="special">{</phrase>
   <phrase role="comment">//
</phrase>   <phrase role="comment">// We can copy with memcpy if T has a trivial assignment operator,
</phrase>   <phrase role="comment">// and if the iterator arguments are actually pointers (this last
</phrase>   <phrase role="comment">// requirement we detect with overload resolution):
</phrase>   <phrase role="comment">//
</phrase>   <phrase role="keyword">typedef</phrase> <phrase role="keyword">typename</phrase> <phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">iterator_traits</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">I1</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase> <phrase role="identifier">value_type</phrase><phrase role="special">;</phrase>
   <phrase role="keyword">return</phrase> <phrase role="identifier">detail</phrase><phrase role="special">::</phrase><phrase role="identifier">copy_imp</phrase><phrase role="special">(</phrase><phrase role="identifier">first</phrase><phrase role="special">,</phrase> <phrase role="identifier">last</phrase><phrase role="special">,</phrase> <phrase role="identifier">out</phrase><phrase role="special">,</phrase> <phrase role="identifier">boost</phrase><phrase role="special">::</phrase><link linkend="boost_typetraits.reference.has_trivial_assign">has_trivial_assign</link><phrase role="special">&lt;</phrase><phrase role="identifier">value_type</phrase><phrase role="special">&gt;());</phrase>
<phrase role="special">}</phrase>
</programlisting>
    </section>
    <section id="boost_typetraits.examples.fill">
      <title><link linkend="boost_typetraits.examples.fill"> An Optimised Version
      of std::fill</link></title>
      <para>
        Demonstrates a version of <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">fill</phrase></computeroutput>
        that uses <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.has_trivial_assign">has_trivial_assign</link></computeroutput>
        to determine whether to use <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">memset</phrase></computeroutput>
        to optimise the fill operation (see <ulink url="../../examples/fill_example.cpp">fill_example.cpp</ulink>):
      </para>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="comment">//
</phrase><phrase role="comment">// fill
</phrase><phrase role="comment">// same as std::fill, but uses memset where appropriate
</phrase><phrase role="comment">//
</phrase><phrase role="keyword">namespace</phrase> <phrase role="identifier">detail</phrase><phrase role="special">{</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">typename</phrase> <phrase role="identifier">I</phrase><phrase role="special">,</phrase> <phrase role="keyword">typename</phrase> <phrase role="identifier">T</phrase><phrase role="special">,</phrase> <phrase role="keyword">bool</phrase> <phrase role="identifier">b</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">void</phrase> <phrase role="identifier">do_fill</phrase><phrase role="special">(</phrase><phrase role="identifier">I</phrase> <phrase role="identifier">first</phrase><phrase role="special">,</phrase> <phrase role="identifier">I</phrase> <phrase role="identifier">last</phrase><phrase role="special">,</phrase> <phrase role="keyword">const</phrase> <phrase role="identifier">T</phrase><phrase role="special">&amp;</phrase> <phrase role="identifier">val</phrase><phrase role="special">,</phrase> <phrase role="keyword">const</phrase> <phrase role="identifier">boost</phrase><phrase role="special">::</phrase><link linkend="boost_typetraits.reference.integral_constant">integral_constant</link><phrase role="special">&lt;</phrase><phrase role="keyword">bool</phrase><phrase role="special">,</phrase> <phrase role="identifier">b</phrase><phrase role="special">&gt;&amp;)</phrase>
<phrase role="special">{</phrase>
   <phrase role="keyword">while</phrase><phrase role="special">(</phrase><phrase role="identifier">first</phrase> <phrase role="special">!=</phrase> <phrase role="identifier">last</phrase><phrase role="special">)</phrase>
   <phrase role="special">{</phrase>
      <phrase role="special">*</phrase><phrase role="identifier">first</phrase> <phrase role="special">=</phrase> <phrase role="identifier">val</phrase><phrase role="special">;</phrase>
      <phrase role="special">++</phrase><phrase role="identifier">first</phrase><phrase role="special">;</phrase>
   <phrase role="special">}</phrase>
<phrase role="special">}</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">typename</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">void</phrase> <phrase role="identifier">do_fill</phrase><phrase role="special">(</phrase><phrase role="identifier">T</phrase><phrase role="special">*</phrase> <phrase role="identifier">first</phrase><phrase role="special">,</phrase> <phrase role="identifier">T</phrase><phrase role="special">*</phrase> <phrase role="identifier">last</phrase><phrase role="special">,</phrase> <phrase role="keyword">const</phrase> <phrase role="identifier">T</phrase><phrase role="special">&amp;</phrase> <phrase role="identifier">val</phrase><phrase role="special">,</phrase> <phrase role="keyword">const</phrase> <phrase role="identifier">boost</phrase><phrase role="special">::</phrase><link linkend="boost_typetraits.reference.integral_constant">true_type</link><phrase role="special">&amp;)</phrase>
<phrase role="special">{</phrase>
   <phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">memset</phrase><phrase role="special">(</phrase><phrase role="identifier">first</phrase><phrase role="special">,</phrase> <phrase role="identifier">val</phrase><phrase role="special">,</phrase> <phrase role="identifier">last</phrase><phrase role="special">-</phrase><phrase role="identifier">first</phrase><phrase role="special">);</phrase>
<phrase role="special">}</phrase>

<phrase role="special">}</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">I</phrase><phrase role="special">,</phrase> <phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">inline</phrase> <phrase role="keyword">void</phrase> <phrase role="identifier">fill</phrase><phrase role="special">(</phrase><phrase role="identifier">I</phrase> <phrase role="identifier">first</phrase><phrase role="special">,</phrase> <phrase role="identifier">I</phrase> <phrase role="identifier">last</phrase><phrase role="special">,</phrase> <phrase role="keyword">const</phrase> <phrase role="identifier">T</phrase><phrase role="special">&amp;</phrase> <phrase role="identifier">val</phrase><phrase role="special">)</phrase>
<phrase role="special">{</phrase>
   <phrase role="comment">//
</phrase>   <phrase role="comment">// We can do an optimised fill if T has a trivial assignment 
</phrase>   <phrase role="comment">// operator and if it's size is one:
</phrase>   <phrase role="comment">//
</phrase>   <phrase role="keyword">typedef</phrase> <phrase role="identifier">boost</phrase><phrase role="special">::</phrase><link linkend="boost_typetraits.reference.integral_constant">integral_constant</link><phrase role="special">&lt;</phrase><phrase role="keyword">bool</phrase><phrase role="special">,</phrase> 
      <phrase role="special">::</phrase><phrase role="identifier">boost</phrase><phrase role="special">::</phrase><link linkend="boost_typetraits.reference.has_trivial_assign">has_trivial_assign</link><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase> <phrase role="special">&amp;&amp;</phrase> <phrase role="special">(</phrase><phrase role="keyword">sizeof</phrase><phrase role="special">(</phrase><phrase role="identifier">T</phrase><phrase role="special">)</phrase> <phrase role="special">==</phrase> <phrase role="number">1</phrase><phrase role="special">)&gt;</phrase> <phrase role="identifier">truth_type</phrase><phrase role="special">;</phrase>
   <phrase role="identifier">detail</phrase><phrase role="special">::</phrase><phrase role="identifier">do_fill</phrase><phrase role="special">(</phrase><phrase role="identifier">first</phrase><phrase role="special">,</phrase> <phrase role="identifier">last</phrase><phrase role="special">,</phrase> <phrase role="identifier">val</phrase><phrase role="special">,</phrase> <phrase role="identifier">truth_type</phrase><phrase role="special">());</phrase>
<phrase role="special">}</phrase>
</programlisting>
    </section>
    <section id="boost_typetraits.examples.destruct">
      <title><link linkend="boost_typetraits.examples.destruct"> An Example that
      Omits Destructor Calls For Types with Trivial Destructors</link></title>
      <para>
        Demonstrates a simple algorithm that uses <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">__has_trivial_destruct</phrase></computeroutput>
        to determine whether to destructors need to be called (see <ulink url="../../examples/trivial_destructor_example.cpp">trivial_destructor_example.cpp</ulink>):
      </para>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="comment">//
</phrase><phrase role="comment">// algorithm destroy_array:
</phrase><phrase role="comment">// The reverse of std::unitialized_copy, takes a block of
</phrase><phrase role="comment">// initialized memory and calls destructors on all objects therein.
</phrase><phrase role="comment">//
</phrase>
<phrase role="keyword">namespace</phrase> <phrase role="identifier">detail</phrase><phrase role="special">{</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">void</phrase> <phrase role="identifier">do_destroy_array</phrase><phrase role="special">(</phrase><phrase role="identifier">T</phrase><phrase role="special">*</phrase> <phrase role="identifier">first</phrase><phrase role="special">,</phrase> <phrase role="identifier">T</phrase><phrase role="special">*</phrase> <phrase role="identifier">last</phrase><phrase role="special">,</phrase> <phrase role="keyword">const</phrase> <phrase role="identifier">boost</phrase><phrase role="special">::</phrase><link linkend="boost_typetraits.reference.integral_constant">false_type</link><phrase role="special">&amp;)</phrase>
<phrase role="special">{</phrase>
   <phrase role="keyword">while</phrase><phrase role="special">(</phrase><phrase role="identifier">first</phrase> <phrase role="special">!=</phrase> <phrase role="identifier">last</phrase><phrase role="special">)</phrase>
   <phrase role="special">{</phrase>
      <phrase role="identifier">first</phrase><phrase role="special">-&gt;~</phrase><phrase role="identifier">T</phrase><phrase role="special">();</phrase>
      <phrase role="special">++</phrase><phrase role="identifier">first</phrase><phrase role="special">;</phrase>
   <phrase role="special">}</phrase>
<phrase role="special">}</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">inline</phrase> <phrase role="keyword">void</phrase> <phrase role="identifier">do_destroy_array</phrase><phrase role="special">(</phrase><phrase role="identifier">T</phrase><phrase role="special">*</phrase> <phrase role="identifier">first</phrase><phrase role="special">,</phrase> <phrase role="identifier">T</phrase><phrase role="special">*</phrase> <phrase role="identifier">last</phrase><phrase role="special">,</phrase> <phrase role="keyword">const</phrase> <phrase role="identifier">boost</phrase><phrase role="special">::</phrase><link linkend="boost_typetraits.reference.integral_constant">true_type</link><phrase role="special">&amp;)</phrase>
<phrase role="special">{</phrase>
<phrase role="special">}</phrase>

<phrase role="special">}</phrase> <phrase role="comment">// namespace detail
</phrase>
<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">inline</phrase> <phrase role="keyword">void</phrase> <phrase role="identifier">destroy_array</phrase><phrase role="special">(</phrase><phrase role="identifier">T</phrase><phrase role="special">*</phrase> <phrase role="identifier">p1</phrase><phrase role="special">,</phrase> <phrase role="identifier">T</phrase><phrase role="special">*</phrase> <phrase role="identifier">p2</phrase><phrase role="special">)</phrase>
<phrase role="special">{</phrase>
   <phrase role="identifier">detail</phrase><phrase role="special">::</phrase><phrase role="identifier">do_destroy_array</phrase><phrase role="special">(</phrase><phrase role="identifier">p1</phrase><phrase role="special">,</phrase> <phrase role="identifier">p2</phrase><phrase role="special">,</phrase> <phrase role="special">::</phrase><phrase role="identifier">boost</phrase><phrase role="special">::</phrase><link linkend="boost_typetraits.reference.has_trivial_destructor">has_trivial_destructor</link><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;());</phrase>
<phrase role="special">}</phrase>
</programlisting>
    </section>
    <section id="boost_typetraits.examples.iter">
      <title><link linkend="boost_typetraits.examples.iter"> An improved Version
      of std::iter_swap</link></title>
      <para>
        Demonstrates a version of <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">iter_swap</phrase></computeroutput>
        that use type traits to determine whether an it's arguments are proxying
        iterators or not, if they're not then it just does a <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">swap</phrase></computeroutput>
        of it's dereferenced arguments (the same as <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">iter_swap</phrase></computeroutput>
        does), however if they are proxying iterators then takes special care over
        the swap to ensure that the algorithm works correctly for both proxying iterators,
        and even iterators of different types (see <ulink url="../../examples/iter_swap_example.cpp">iter_swap_example.cpp</ulink>):
      </para>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="comment">//
</phrase><phrase role="comment">// iter_swap:
</phrase><phrase role="comment">// tests whether iterator is a proxying iterator or not, and
</phrase><phrase role="comment">// uses optimal form accordingly:
</phrase><phrase role="comment">//
</phrase><phrase role="keyword">namespace</phrase> <phrase role="identifier">detail</phrase><phrase role="special">{</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">typename</phrase> <phrase role="identifier">I</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">static</phrase> <phrase role="keyword">void</phrase> <phrase role="identifier">do_swap</phrase><phrase role="special">(</phrase><phrase role="identifier">I</phrase> <phrase role="identifier">one</phrase><phrase role="special">,</phrase> <phrase role="identifier">I</phrase> <phrase role="identifier">two</phrase><phrase role="special">,</phrase> <phrase role="keyword">const</phrase> <phrase role="identifier">boost</phrase><phrase role="special">::</phrase><link linkend="boost_typetraits.reference.integral_constant">false_type</link><phrase role="special">&amp;)</phrase>
<phrase role="special">{</phrase>
   <phrase role="keyword">typedef</phrase> <phrase role="keyword">typename</phrase> <phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">iterator_traits</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">I</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase> <phrase role="identifier">v_t</phrase><phrase role="special">;</phrase>
   <phrase role="identifier">v_t</phrase> <phrase role="identifier">v</phrase> <phrase role="special">=</phrase> <phrase role="special">*</phrase><phrase role="identifier">one</phrase><phrase role="special">;</phrase>
   <phrase role="special">*</phrase><phrase role="identifier">one</phrase> <phrase role="special">=</phrase> <phrase role="special">*</phrase><phrase role="identifier">two</phrase><phrase role="special">;</phrase>
   <phrase role="special">*</phrase><phrase role="identifier">two</phrase> <phrase role="special">=</phrase> <phrase role="identifier">v</phrase><phrase role="special">;</phrase>
<phrase role="special">}</phrase>
<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">typename</phrase> <phrase role="identifier">I</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">static</phrase> <phrase role="keyword">void</phrase> <phrase role="identifier">do_swap</phrase><phrase role="special">(</phrase><phrase role="identifier">I</phrase> <phrase role="identifier">one</phrase><phrase role="special">,</phrase> <phrase role="identifier">I</phrase> <phrase role="identifier">two</phrase><phrase role="special">,</phrase> <phrase role="keyword">const</phrase> <phrase role="identifier">boost</phrase><phrase role="special">::</phrase><link linkend="boost_typetraits.reference.integral_constant">true_type</link><phrase role="special">&amp;)</phrase>
<phrase role="special">{</phrase>
   <phrase role="keyword">using</phrase> <phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">swap</phrase><phrase role="special">;</phrase>
   <phrase role="identifier">swap</phrase><phrase role="special">(*</phrase><phrase role="identifier">one</phrase><phrase role="special">,</phrase> <phrase role="special">*</phrase><phrase role="identifier">two</phrase><phrase role="special">);</phrase>
<phrase role="special">}</phrase>

<phrase role="special">}</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">typename</phrase> <phrase role="identifier">I1</phrase><phrase role="special">,</phrase> <phrase role="keyword">typename</phrase> <phrase role="identifier">I2</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">inline</phrase> <phrase role="keyword">void</phrase> <phrase role="identifier">iter_swap</phrase><phrase role="special">(</phrase><phrase role="identifier">I1</phrase> <phrase role="identifier">one</phrase><phrase role="special">,</phrase> <phrase role="identifier">I2</phrase> <phrase role="identifier">two</phrase><phrase role="special">)</phrase>
<phrase role="special">{</phrase>
   <phrase role="comment">//
</phrase>   <phrase role="comment">// See is both arguments are non-proxying iterators, 
</phrase>   <phrase role="comment">// and if both iterator the same type:
</phrase>   <phrase role="comment">//
</phrase>   <phrase role="keyword">typedef</phrase> <phrase role="keyword">typename</phrase> <phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">iterator_traits</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">I1</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">reference</phrase> <phrase role="identifier">r1_t</phrase><phrase role="special">;</phrase>
   <phrase role="keyword">typedef</phrase> <phrase role="keyword">typename</phrase> <phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">iterator_traits</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">I2</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">reference</phrase> <phrase role="identifier">r2_t</phrase><phrase role="special">;</phrase>

   <phrase role="keyword">typedef</phrase> <phrase role="identifier">boost</phrase><phrase role="special">::</phrase><link linkend="boost_typetraits.reference.integral_constant">integral_constant</link><phrase role="special">&lt;</phrase><phrase role="keyword">bool</phrase><phrase role="special">,</phrase>
      <phrase role="special">::</phrase><phrase role="identifier">boost</phrase><phrase role="special">::</phrase><link linkend="boost_typetraits.reference.is_reference">is_reference</link><phrase role="special">&lt;</phrase><phrase role="identifier">r1_t</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase>
      <phrase role="special">&amp;&amp;</phrase> <phrase role="special">::</phrase><phrase role="identifier">boost</phrase><phrase role="special">::</phrase><link linkend="boost_typetraits.reference.is_reference">is_reference</link><phrase role="special">&lt;</phrase><phrase role="identifier">r2_t</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase>
      <phrase role="special">&amp;&amp;</phrase> <phrase role="special">::</phrase><phrase role="identifier">boost</phrase><phrase role="special">::</phrase><link linkend="boost_typetraits.reference.is_same">is_same</link><phrase role="special">&lt;</phrase><phrase role="identifier">r1_t</phrase><phrase role="special">,</phrase> <phrase role="identifier">r2_t</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase><phrase role="special">&gt;</phrase> <phrase role="identifier">truth_type</phrase><phrase role="special">;</phrase>

   <phrase role="identifier">detail</phrase><phrase role="special">::</phrase><phrase role="identifier">do_swap</phrase><phrase role="special">(</phrase><phrase role="identifier">one</phrase><phrase role="special">,</phrase> <phrase role="identifier">two</phrase><phrase role="special">,</phrase> <phrase role="identifier">truth_type</phrase><phrase role="special">());</phrase>
<phrase role="special">}</phrase>
</programlisting>
    </section>
    <section id="boost_typetraits.examples.to_double">
      <title><link linkend="boost_typetraits.examples.to_double"> Convert Numeric
      Types and Enums to double</link></title>
      <para>
        Demonstrates a conversion of <ulink url="../../../../libs/numeric/conversion/doc/html/boost_numericconversion/definitions.html#boost_numericconversion.definitions.numeric_types">Numeric
        Types</ulink> and enum types to double:
      </para>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">inline</phrase> <phrase role="keyword">double</phrase> <phrase role="identifier">to_double</phrase><phrase role="special">(</phrase><phrase role="identifier">T</phrase> <phrase role="keyword">const</phrase><phrase role="special">&amp;</phrase> <phrase role="identifier">value</phrase><phrase role="special">)</phrase>
<phrase role="special">{</phrase>
    <phrase role="keyword">typedef</phrase> <phrase role="keyword">typename</phrase> <phrase role="identifier">boost</phrase><phrase role="special">::</phrase><phrase role="identifier">promote</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase> <phrase role="identifier">promoted</phrase><phrase role="special">;</phrase>
    <phrase role="keyword">return</phrase> <phrase role="identifier">boost</phrase><phrase role="special">::</phrase><phrase role="identifier">numeric</phrase><phrase role="special">::</phrase><phrase role="identifier">converter</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">double</phrase><phrase role="special">,</phrase><phrase role="identifier">promoted</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">convert</phrase><phrase role="special">(</phrase><phrase role="identifier">value</phrase><phrase role="special">);</phrase>
<phrase role="special">}</phrase>
</programlisting>
    </section>
  </section>
  <section id="boost_typetraits.reference">
    <title><link linkend="boost_typetraits.reference"> Alphabetical Reference</link></title>
    <section id="boost_typetraits.reference.add_const"><indexterm type="class_name"><primary>Constrained Index Term</primary><secondary>add_const</secondary></indexterm><indexterm><primary>add_const</primary><secondary>Constrained Index Term</secondary></indexterm><indexterm type="class_name"><primary>Constrained Index Term</primary><secondary>add_const</secondary></indexterm><indexterm><primary>add_const</primary><secondary>Constrained Index Term</secondary></indexterm><indexterm type="class_name"><primary>add_const</primary><secondary>add_const</secondary></indexterm><indexterm type="class_name"><primary>Constrained Index Term</primary><secondary>add_const</secondary></indexterm><indexterm><primary>add_const</primary><secondary>Constrained Index Term</secondary></indexterm><indexterm type="class_name"><primary>Constrained Index Term</primary><secondary>add_const</secondary></indexterm><indexterm><primary>add_const</primary><secondary>Constrained Index Term</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.add_const"> add_const</link></title>
       <indexterm type="class_name">
          <primary>one</primary>
          <secondary>two</secondary>
       </indexterm>

       <programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">add_const</phrase>
<phrase role="special">{</phrase>
   <phrase role="keyword">typedef</phrase> <replaceable>see-below</replaceable> <phrase role="identifier">type</phrase><phrase role="special">;</phrase>
<phrase role="special">};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">type:</emphasis> The same type as <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase>
        <phrase role="keyword">const</phrase></computeroutput> for all <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 3.9.3.
      </para>
      <para>
        <emphasis role="bold">Compiler Compatibility:</emphasis> If the compiler
        does not support partial specialization of class-templates then this template
        will compile, but the member <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">type</phrase></computeroutput>
        will always be the same as type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>
        except where <link linkend="boost_typetraits.category.transform.broken_compiler_workarounds_">compiler
        workarounds</link> have been applied.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">add_const</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <table frame="all"> <title>Examples</title>
      <tgroup cols="2">
        <thead>
          <row>
            <entry>
            <para>
              Expression
            </para>
            </entry><entry>
            <para>
              Result Type
            </para>
            </entry>
          </row>
        </thead>
        <tbody>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">add_const</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">add_const</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">&amp;&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase><phrase role="special">&amp;</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">add_const</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">*&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase><phrase role="special">*</phrase>
              <phrase role="keyword">const</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">add_const</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase></computeroutput>
            </para>
            </entry>
          </row>
        </tbody>
      </tgroup>
      </table>
    </section>
    <section id="boost_typetraits.reference.add_cv"><indexterm type="class_name"><primary>add_cv</primary><secondary>add_cv</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.add_cv"> add_cv</link></title>
       <indexterm type="class_name">
          <primary>one</primary>
          <secondary>two</secondary>
          <tertiary>three</tertiary>
       </indexterm>

       <programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">add_cv</phrase>
<phrase role="special">{</phrase>
   <phrase role="keyword">typedef</phrase> <replaceable>see-below</replaceable> <phrase role="identifier">type</phrase><phrase role="special">;</phrase>
<phrase role="special">};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">type:</emphasis> The same type as <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase>
        <phrase role="keyword">const</phrase> <phrase role="keyword">volatile</phrase></computeroutput>
        for all <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 3.9.3.
      </para>
      <para>
        <emphasis role="bold">Compiler Compatibility:</emphasis> If the compiler
        does not support partial specialization of class-templates then this template
        will compile, but the member <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">type</phrase></computeroutput>
        will always be the same as type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>
        except where <link linkend="boost_typetraits.category.transform.broken_compiler_workarounds_">compiler
        workarounds</link> have been applied.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">add_cv</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <table frame="all"> <title>Examples</title>
      <tgroup cols="2">
        <thead>
          <row>
            <entry>
            <para>
              Expression
            </para>
            </entry><entry>
            <para>
              Result Type
            </para>
            </entry>
          </row>
        </thead>
        <tbody>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">add_cv</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase>
              <phrase role="keyword">volatile</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">add_cv</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">&amp;&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase><phrase role="special">&amp;</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">add_cv</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">*&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase><phrase role="special">*</phrase>
              <phrase role="keyword">const</phrase> <phrase role="keyword">volatile</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">add_cv</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase>
              <phrase role="keyword">volatile</phrase></computeroutput>
            </para>
            </entry>
          </row>
        </tbody>
      </tgroup>
      </table>
    </section>
    <section id="boost_typetraits.reference.add_pointer"><indexterm type="class_name"><primary>add_pointer</primary><secondary>add_pointer</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.add_pointer"> add_pointer</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">add_pointer</phrase>
<phrase role="special">{</phrase>
   <phrase role="keyword">typedef</phrase> <replaceable>see-below</replaceable> <phrase role="identifier">type</phrase><phrase role="special">;</phrase>
<phrase role="special">};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">type:</emphasis> The same type as <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_reference</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase><phrase role="special">*</phrase></computeroutput>.
      </para>
      <para>
        The rationale for this template is that it produces the same type as <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">TYPEOF</phrase><phrase role="special">(&amp;</phrase><phrase role="identifier">t</phrase><phrase role="special">)</phrase></computeroutput>, where
        <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">t</phrase></computeroutput> is an object of type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 8.3.1.
      </para>
      <para>
        <emphasis role="bold">Compiler Compatibility:</emphasis> If the compiler
        does not support partial specialization of class-templates then this template
        will compile, but the member <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">type</phrase></computeroutput>
        will always be the same as type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>
        except where <link linkend="boost_typetraits.category.transform.broken_compiler_workarounds_">compiler
        workarounds</link> have been applied.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">add_pointer</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <table frame="all"> <title>Examples</title>
      <tgroup cols="2">
        <thead>
          <row>
            <entry>
            <para>
              Expression
            </para>
            </entry><entry>
            <para>
              Result Type
            </para>
            </entry>
          </row>
        </thead>
        <tbody>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">add_pointer</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase><phrase role="special">*</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">add_pointer</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase><phrase role="special">&amp;&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase><phrase role="special">*</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">add_pointer</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">*&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase><phrase role="special">**</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">add_pointer</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">*&amp;&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase><phrase role="special">**</phrase></computeroutput>
            </para>
            </entry>
          </row>
        </tbody>
      </tgroup>
      </table>
    </section>
    <section id="boost_typetraits.reference.add_reference"><indexterm type="class_name"><primary>add_reference</primary><secondary>add_reference</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.add_reference"> add_reference</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">add_reference</phrase>
<phrase role="special">{</phrase>
   <phrase role="keyword">typedef</phrase> <replaceable>see-below</replaceable> <phrase role="identifier">type</phrase><phrase role="special">;</phrase>
<phrase role="special">};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">type:</emphasis> If <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>
        is not a reference type then <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase><phrase role="special">&amp;</phrase></computeroutput>, otherwise <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 8.3.2.
      </para>
      <para>
        <emphasis role="bold">Compiler Compatibility:</emphasis> If the compiler
        does not support partial specialization of class-templates then this template
        will compile, but the member <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">type</phrase></computeroutput>
        will always be the same as type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>
        except where <link linkend="boost_typetraits.category.transform.broken_compiler_workarounds_">compiler
        workarounds</link> have been applied.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">add_reference</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <table frame="all"> <title>Examples</title>
      <tgroup cols="2">
        <thead>
          <row>
            <entry>
            <para>
              Expression
            </para>
            </entry><entry>
            <para>
              Result Type
            </para>
            </entry>
          </row>
        </thead>
        <tbody>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">add_reference</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase><phrase role="special">&amp;</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">add_reference</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase><phrase role="special">&amp;&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase><phrase role="special">&amp;</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">add_reference</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">*&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase><phrase role="special">*&amp;</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">add_reference</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">*&amp;&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase><phrase role="special">*&amp;</phrase></computeroutput>
            </para>
            </entry>
          </row>
        </tbody>
      </tgroup>
      </table>
    </section>
    <section id="boost_typetraits.reference.add_volatile"><indexterm type="class_name"><primary>add_volatile</primary><secondary>add_volatile</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.add_volatile"> add_volatile</link></title>
       <indexterm type="class_name">
          <primary>one</primary>
       </indexterm>

       <programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">add_volatile</phrase>
<phrase role="special">{</phrase>
   <phrase role="keyword">typedef</phrase> <replaceable>see-below</replaceable> <phrase role="identifier">type</phrase><phrase role="special">;</phrase>
<phrase role="special">};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">type:</emphasis> The same type as <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase>
        <phrase role="keyword">volatile</phrase></computeroutput> for all <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 3.9.3.
      </para>
      <para>
        <emphasis role="bold">Compiler Compatibility:</emphasis> If the compiler
        does not support partial specialization of class-templates then this template
        will compile, but the member <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">type</phrase></computeroutput>
        will always be the same as type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>
        except where <link linkend="boost_typetraits.category.transform.broken_compiler_workarounds_">compiler
        workarounds</link> have been applied.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">add_volatile</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <table frame="all"> <title>Examples</title>
      <tgroup cols="2">
        <thead>
          <row>
            <entry>
            <para>
              Expression
            </para>
            </entry><entry>
            <para>
              Result Type
            </para>
            </entry>
          </row>
        </thead>
        <tbody>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">add_volatile</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase> <phrase role="keyword">volatile</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">add_volatile</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">&amp;&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase><phrase role="special">&amp;</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">add_volatile</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">*&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase><phrase role="special">*</phrase>
              <phrase role="keyword">volatile</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">add_volatile</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase>
              <phrase role="keyword">volatile</phrase></computeroutput>
            </para>
            </entry>
          </row>
        </tbody>
      </tgroup>
      </table>
    </section>
    <section id="boost_typetraits.reference.aligned_storage"><indexterm type="class_name"><primary>aligned_storage</primary><secondary>aligned_storage</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.aligned_storage"> aligned_storage</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">size_t</phrase> <phrase role="identifier">Size</phrase><phrase role="special">,</phrase> <phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">size_t</phrase> <phrase role="identifier">Align</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">aligned_storage</phrase>
<phrase role="special">{</phrase>
   <phrase role="keyword">typedef</phrase> <replaceable>see-below</replaceable> <phrase role="identifier">type</phrase><phrase role="special">;</phrase>
<phrase role="special">};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">type:</emphasis> a built-in or POD type with size
        <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">Size</phrase></computeroutput> and an alignment that
        is a multiple of <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">Align</phrase></computeroutput>.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">aligned_storage</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
    </section>
    <section id="boost_typetraits.reference.alignment_of"><indexterm type="class_name"><primary>integral_constant</primary><secondary>alignment_of</secondary></indexterm><indexterm><primary>alignment_of</primary><secondary>integral_constant</secondary></indexterm><indexterm type="class_name"><primary>alignment_of</primary><secondary>alignment_of</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.alignment_of"> alignment_of</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">alignment_of</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <link linkend="boost_typetraits.reference.integral_constant">integral_constant</link><phrase role="special">&lt;</phrase><phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">size_t</phrase><phrase role="special">,</phrase> <phrase role="identifier">ALIGNOF</phrase><phrase role="special">(</phrase><phrase role="identifier">T</phrase><phrase role="special">)&gt;</phrase> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> Class template alignment<emphasis role="underline">of inherits from `</emphasis>_integral_constant&lt;std::size_t,
        ALIGNOF(T)&gt;<computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="special">,</phrase> <phrase role="identifier">where</phrase>
        </computeroutput>ALIGNOF(T)` is the alignment of type T.
      </para>
      <para>
        <emphasis>Note: strictly speaking you should only rely on the value of <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">ALIGNOF</phrase><phrase role="special">(</phrase><phrase role="identifier">T</phrase><phrase role="special">)</phrase></computeroutput> being
        a multiple of the true alignment of T, although in practice it does compute
        the correct value in all the cases we know about.</emphasis>
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">alignment_of</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Examples:</emphasis>
      </para>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">alignment_of</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">&gt;</phrase></computeroutput>
            inherits from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">integral_constant</link><phrase role="special">&lt;</phrase><phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">size_t</phrase><phrase role="special">,</phrase> <phrase role="identifier">ALIGNOF</phrase><phrase role="special">(</phrase><phrase role="keyword">int</phrase><phrase role="special">)&gt;</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">alignment_of</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">char</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">integral_constant</link><phrase role="special">&lt;</phrase><phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">size_t</phrase><phrase role="special">,</phrase> <phrase role="identifier">ALIGNOF</phrase><phrase role="special">(</phrase><phrase role="keyword">char</phrase><phrase role="special">)&gt;</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">alignment_of</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">double</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            with value <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">ALIGNOF</phrase><phrase role="special">(</phrase><phrase role="keyword">double</phrase><phrase role="special">)</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">alignment_of</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">size_t</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
    </section>
    <section id="boost_typetraits.reference.decay"><indexterm type="class_name"><primary>decay</primary><secondary>decay</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.decay"> decay</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">decay</phrase>
<phrase role="special">{</phrase>
   <phrase role="keyword">typedef</phrase> <replaceable>see-below</replaceable> <phrase role="identifier">type</phrase><phrase role="special">;</phrase>
<phrase role="special">};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">type:</emphasis> Let <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">U</phrase></computeroutput>
        be the result of <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_reference</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>, then if <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">U</phrase></computeroutput>
        is an array type, the result is <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_extent</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">U</phrase><phrase role="special">&gt;*</phrase></computeroutput>,
        otherwise if <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">U</phrase></computeroutput> is a function
        type then the result is <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">U</phrase><phrase role="special">*</phrase></computeroutput>, otherwise the result is <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">U</phrase></computeroutput>.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 3.9.1.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">decay</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <table frame="all"> <title>Examples</title>
      <tgroup cols="2">
        <thead>
          <row>
            <entry>
            <para>
              Expression
            </para>
            </entry><entry>
            <para>
              Result Type
            </para>
            </entry>
          </row>
        </thead>
        <tbody>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">decay</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">[</phrase><phrase role="number">2</phrase><phrase role="special">][</phrase><phrase role="number">3</phrase><phrase role="special">]&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase><phrase role="special">[</phrase><phrase role="number">2</phrase><phrase role="special">]*</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">decay</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">(&amp;)[</phrase><phrase role="number">2</phrase><phrase role="special">]&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase><phrase role="special">*</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">decay</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">(&amp;)(</phrase><phrase role="keyword">double</phrase><phrase role="special">)&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase><phrase role="special">(*)(</phrase><phrase role="keyword">double</phrase><phrase role="special">)</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase><phrase role="special">(*)(</phrase><phrase role="keyword">double</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase><phrase role="special">(*)(</phrase><phrase role="keyword">double</phrase><phrase role="special">)</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase><phrase role="special">(</phrase><phrase role="keyword">double</phrase><phrase role="special">)</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase><phrase role="special">(*)(</phrase><phrase role="keyword">double</phrase><phrase role="special">)</phrase></computeroutput>
            </para>
            </entry>
          </row>
        </tbody>
      </tgroup>
      </table>
    </section>
    <section id="boost_typetraits.reference.extent"><indexterm type="class_name"><primary>integral_constant</primary><secondary>extent</secondary></indexterm><indexterm><primary>extent</primary><secondary>integral_constant</secondary></indexterm><indexterm type="class_name"><primary>extent</primary><secondary>extent</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.extent"> extent</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">,</phrase> <phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">size_t</phrase> <phrase role="identifier">N</phrase> <phrase role="special">=</phrase> <phrase role="number">0</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">extent</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <link linkend="boost_typetraits.reference.integral_constant">integral_constant</link><phrase role="special">&lt;</phrase><phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">size_t</phrase><phrase role="special">,</phrase> <phrase role="identifier">EXTENT</phrase><phrase role="special">(</phrase><phrase role="identifier">T</phrase><phrase role="special">,</phrase><phrase role="identifier">N</phrase><phrase role="special">)&gt;</phrase> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> Class template extent inherits
        from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">integral_constant</link><phrase role="special">&lt;</phrase><phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">size_t</phrase><phrase role="special">,</phrase> <phrase role="identifier">EXTENT</phrase><phrase role="special">(</phrase><phrase role="identifier">T</phrase><phrase role="special">,</phrase><phrase role="identifier">N</phrase><phrase role="special">)&gt;</phrase></computeroutput>,
        where <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">EXTENT</phrase><phrase role="special">(</phrase><phrase role="identifier">T</phrase><phrase role="special">,</phrase><phrase role="identifier">N</phrase><phrase role="special">)</phrase></computeroutput> is the number of elements in the N'th array
        dimention of type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>.
      </para>
      <para>
        If <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput> is not an array type,
        or if <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">N</phrase> <phrase role="special">&gt;</phrase>
        <link linkend="boost_typetraits.reference.rank">rank</link><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput>, or if the N'th array bound is incomplete,
        then <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">EXTENT</phrase><phrase role="special">(</phrase><phrase role="identifier">T</phrase><phrase role="special">,</phrase><phrase role="identifier">N</phrase><phrase role="special">)</phrase></computeroutput> is zero.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">extent</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Examples:</emphasis>
      </para>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">extent</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">[</phrase><phrase role="number">1</phrase><phrase role="special">]&gt;</phrase></computeroutput> inherits from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">integral_constant</link><phrase role="special">&lt;</phrase><phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">size_t</phrase><phrase role="special">,</phrase> <phrase role="number">1</phrase><phrase role="special">&gt;</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">extent</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">double</phrase><phrase role="special">[</phrase><phrase role="number">2</phrase><phrase role="special">][</phrase><phrase role="number">3</phrase><phrase role="special">][</phrase><phrase role="number">4</phrase><phrase role="special">],</phrase>
            <phrase role="number">1</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">integral_constant</link><phrase role="special">&lt;</phrase><phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">size_t</phrase><phrase role="special">,</phrase> <phrase role="number">3</phrase><phrase role="special">&gt;</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">extent</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">[</phrase><phrase role="number">4</phrase><phrase role="special">]&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput>
            is an integral constant expression that evaluates to <emphasis>4</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">extent</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">[][</phrase><phrase role="number">2</phrase><phrase role="special">]&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>0</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">extent</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">[][</phrase><phrase role="number">2</phrase><phrase role="special">],</phrase> <phrase role="number">1</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput>
            is an integral constant expression that evaluates to <emphasis>2</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">extent</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">*&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>0</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">extent</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">size_t</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
    </section>
    <section id="boost_typetraits.reference.floating_point_promotion"><indexterm type="class_name"><primary>floating_point_promotion</primary><secondary>floating_point_promotion</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.floating_point_promotion">
      floating_point_promotion</link></title> 
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">floating_point_promotion</phrase>
<phrase role="special">{</phrase>
   <phrase role="keyword">typedef</phrase> <replaceable>see-below</replaceable> <phrase role="identifier">type</phrase><phrase role="special">;</phrase>
<phrase role="special">};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">type:</emphasis> If floating point promotion can be
        applied to an rvalue of type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>,
        then applies floating point promotion to <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>
        and keeps cv-qualifiers of <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>,
        otherwise leaves <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput> unchanged.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 4.6.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">floating_point_promotion</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <table frame="all"> <title>Examples</title>
      <tgroup cols="2">
        <thead>
          <row>
            <entry>
            <para>
              Expression
            </para>
            </entry><entry>
            <para>
              Result Type
            </para>
            </entry>
          </row>
        </thead>
        <tbody>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">floating_point_promotion</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">float</phrase>
              <phrase role="keyword">const</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">double</phrase> <phrase role="keyword">const</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">floating_point_promotion</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">float</phrase><phrase role="special">&amp;&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">float</phrase><phrase role="special">&amp;</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">floating_point_promotion</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">short</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">short</phrase></computeroutput>
            </para>
            </entry>
          </row>
        </tbody>
      </tgroup>
      </table>
    </section>
    <section id="boost_typetraits.reference.function_traits"><indexterm type="typedef_name"><primary>result_type</primary><secondary>function_traits</secondary></indexterm><indexterm><primary>function_traits</primary><secondary>result_type</secondary></indexterm><indexterm type="class_name"><primary>function_traits</primary><secondary>function_traits</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.function_traits"> function_traits</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">F</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">function_traits</phrase>
<phrase role="special">{</phrase>
   <phrase role="keyword">static</phrase> <phrase role="keyword">const</phrase> <phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">size_t</phrase>    <phrase role="identifier">arity</phrase> <phrase role="special">=</phrase> <replaceable>see-below</replaceable><phrase role="special">;</phrase>
   <phrase role="keyword">typedef</phrase> <replaceable>see-below</replaceable>           <phrase role="identifier">result_type</phrase><phrase role="special">;</phrase>
   <phrase role="keyword">typedef</phrase> <replaceable>see-below</replaceable>           arg<replaceable>N</replaceable>_type<phrase role="special">;</phrase> 
<phrase role="special">};</phrase>
</programlisting>
      <para>
        The class template function_traits will only compile if:
      </para>
      <itemizedlist>
        <listitem>
          The compiler supports partial specialization of class templates.
        </listitem>
        <listitem>
          The template argument <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">F</phrase></computeroutput>
          is a <emphasis>function type</emphasis>, note that this <emphasis><emphasis role="bold">is not</emphasis></emphasis> the same thing as a <emphasis>pointer
          to a function</emphasis>.
        </listitem>
      </itemizedlist>
      <tip>
        <para>
          function_traits is intended to introspect only C++ functions of the form
          R (), R( A1 ), R ( A1, ... etc. ) and not function pointers or class member
          functions. To convert a function pointer type to a suitable type use <link linkend="boost_typetraits.reference.remove_pointer">remove_pointer</link>.
        </para>
      </tip>
      <table frame="all"> <title>Function Traits Members</title>
      <tgroup cols="2">
        <thead>
          <row>
            <entry>
            <para>
              Member
            </para>
            </entry><entry>
            <para>
              Description
            </para>
            </entry>
          </row>
        </thead>
        <tbody>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">function_traits</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">F</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">arity</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              An integral constant expression that gives the number of arguments
              accepted by the function type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">F</phrase></computeroutput>.
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">function_traits</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">F</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">result_type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              The type returned by function type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">F</phrase></computeroutput>.
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">function_traits</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">F</phrase><phrase role="special">&gt;::</phrase>arg<replaceable>N</replaceable>_type</computeroutput>
            </para>
            </entry><entry>
            <para>
              The <replaceable>N</replaceable>th argument type of function type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">F</phrase></computeroutput>,
              where <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="number">1</phrase> <phrase role="special">&lt;=</phrase>
              <phrase role="identifier">N</phrase> <phrase role="special">&lt;=</phrase>
              <phrase role="identifier">arity</phrase></computeroutput> of <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">F</phrase></computeroutput>.
            </para>
            </entry>
          </row>
        </tbody>
      </tgroup>
      </table> <table frame="all"> <title>Examples</title>
      <tgroup cols="2">
        <thead>
          <row>
            <entry>
            <para>
              Expression
            </para>
            </entry><entry>
            <para>
              Result
            </para>
            </entry>
          </row>
        </thead>
        <tbody>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">function_traits</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">void</phrase> <phrase role="special">(</phrase><phrase role="keyword">void</phrase><phrase role="special">)&gt;::</phrase><phrase role="identifier">arity</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              An integral constant expression that has the value 0.
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">function_traits</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">long</phrase> <phrase role="special">(</phrase><phrase role="keyword">int</phrase><phrase role="special">)&gt;::</phrase><phrase role="identifier">arity</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              An integral constant expression that has the value 1.
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">function_traits</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">long</phrase> <phrase role="special">(</phrase><phrase role="keyword">int</phrase><phrase role="special">,</phrase> <phrase role="keyword">long</phrase><phrase role="special">,</phrase> <phrase role="keyword">double</phrase><phrase role="special">,</phrase> <phrase role="keyword">void</phrase><phrase role="special">*)&gt;::</phrase><phrase role="identifier">arity</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              An integral constant expression that has the value 4.
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">function_traits</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">void</phrase> <phrase role="special">(</phrase><phrase role="keyword">void</phrase><phrase role="special">)&gt;::</phrase><phrase role="identifier">result_type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              The type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">void</phrase></computeroutput>.
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">function_traits</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">long</phrase> <phrase role="special">(</phrase><phrase role="keyword">int</phrase><phrase role="special">)&gt;::</phrase><phrase role="identifier">result_type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              The type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">long</phrase></computeroutput>.
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">function_traits</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">long</phrase> <phrase role="special">(</phrase><phrase role="keyword">int</phrase><phrase role="special">)&gt;::</phrase><phrase role="identifier">arg1_type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              The type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase></computeroutput>.
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">function_traits</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">long</phrase> <phrase role="special">(</phrase><phrase role="keyword">int</phrase><phrase role="special">,</phrase> <phrase role="keyword">long</phrase><phrase role="special">,</phrase> <phrase role="keyword">double</phrase><phrase role="special">,</phrase> <phrase role="keyword">void</phrase><phrase role="special">*)&gt;::</phrase><phrase role="identifier">arg4_type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              The type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">void</phrase><phrase role="special">*</phrase></computeroutput>.
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">function_traits</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">long</phrase> <phrase role="special">(</phrase><phrase role="keyword">int</phrase><phrase role="special">,</phrase> <phrase role="keyword">long</phrase><phrase role="special">,</phrase> <phrase role="keyword">double</phrase><phrase role="special">,</phrase> <phrase role="keyword">void</phrase><phrase role="special">*)&gt;::</phrase><phrase role="identifier">arg5_type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              A compiler error: there is no <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">arg5_type</phrase></computeroutput>
              since there are only four arguments.
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">function_traits</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">long</phrase> <phrase role="special">(*)(</phrase><phrase role="keyword">void</phrase><phrase role="special">)&gt;::</phrase><phrase role="identifier">arity</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              A compiler error: argument type is a <emphasis>function pointer</emphasis>,
              and not a <emphasis>function type</emphasis>.
            </para>
            </entry>
          </row>
        </tbody>
      </tgroup>
      </table>
    </section>
    <section id="boost_typetraits.reference.has_nothrow_assign"><indexterm type="class_name"><primary>has_nothrow_assign</primary><secondary>has_nothrow_assign</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.has_nothrow_assign"> has_nothrow_assign</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">has_nothrow_assign</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If T is a (possibly cv-qualified)
        type with a non-throwing assignment-operator then inherits from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
        Type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput> must be a complete
        type.
      </para>
      <para>
        <emphasis role="bold">Compiler Compatibility:</emphasis> If the compiler
        does not support partial-specialization of class templates, then this template
        can not be used with function types.
      </para>
      <para>
        Without some (as yet unspecified) help from the compiler, <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">has_nothrow_assign</phrase></computeroutput>
        will never report that a class or struct has a non-throwing assignment-operator;
        this is always safe, if possibly sub-optimal. Currently (May 2005) only Visual
        C++ 8 has the necessary compiler support to ensure that this trait "just
        works".
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">has_nothrow_assign</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
    </section>
    <section id="boost_typetraits.reference.has_nothrow_constructor"><indexterm type="class_name"><primary>has_nothrow_default_constructor</primary><secondary>has_nothrow_constructor</secondary></indexterm><indexterm><primary>has_nothrow_constructor</primary><secondary>has_nothrow_default_constructor</secondary></indexterm><indexterm type="class_name"><primary>has_nothrow_constructor</primary><secondary>has_nothrow_constructor</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.has_nothrow_constructor">
      has_nothrow_constructor</link></title> 
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">has_nothrow_constructor</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">has_nothrow_default_constructor</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If T is a (possibly cv-qualified)
        type with a non-throwing default-constructor then inherits from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
        Type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput> must be a complete
        type.
      </para>
      <para>
        These two traits are synonyms for each other.
      </para>
      <para>
        <emphasis role="bold">Compiler Compatibility:</emphasis> If the compiler
        does not support partial-specialization of class templates, then this template
        can not be used with function types.
      </para>
      <para>
        Without some (as yet unspecified) help from the compiler, <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">has_nothrow_constructor</phrase></computeroutput>
        will never report that a class or struct has a non-throwing default-constructor;
        this is always safe, if possibly sub-optimal. Currently (May 2005) only Visual
        C++ 8 has the necessary compiler <link linkend="boost_typetraits.intrinsics">intrinsics</link>
        to ensure that this trait "just works".
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">has_nothrow_constructor</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
    </section>
    <section id="boost_typetraits.reference.has_nothrow_copy"><indexterm type="class_name"><primary>has_nothrow_copy_constructor</primary><secondary>has_nothrow_copy</secondary></indexterm><indexterm><primary>has_nothrow_copy</primary><secondary>has_nothrow_copy_constructor</secondary></indexterm><indexterm type="class_name"><primary>has_nothrow_copy</primary><secondary>has_nothrow_copy</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.has_nothrow_copy"> has_nothrow_copy</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">has_nothrow_copy</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">has_nothrow_copy_constructor</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If T is a (possibly cv-qualified)
        type with a non-throwing copy-constructor then inherits from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
        Type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput> must be a complete
        type.
      </para>
      <para>
        These two traits are synonyms for each other.
      </para>
      <para>
        <emphasis role="bold">Compiler Compatibility:</emphasis> If the compiler
        does not support partial-specialization of class templates, then this template
        can not be used with function types.
      </para>
      <para>
        Without some (as yet unspecified) help from the compiler, <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">has_nothrow_copy</phrase></computeroutput>
        will never report that a class or struct has a non-throwing copy-constructor;
        this is always safe, if possibly sub-optimal. Currently (May 2005) only Visual
        C++ 8 has the necessary compiler <link linkend="boost_typetraits.intrinsics">intrinsics</link>
        to ensure that this trait "just works".
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">has_nothrow_copy</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
    </section>
    <section id="boost_typetraits.reference.has_nothrow_cp_cons">
      <title><link linkend="boost_typetraits.reference.has_nothrow_cp_cons"> has_nothrow_copy_constructor</link></title>
      <para>
        See <link linkend="boost_typetraits.reference.has_nothrow_copy">has_nothrow_copy</link>.
      </para>
    </section>
    <section id="boost_typetraits.reference.has_no_throw_def_cons">
      <title><link linkend="boost_typetraits.reference.has_no_throw_def_cons"> has_nothrow_default_constructor</link></title>
      <para>
        See <link linkend="boost_typetraits.reference.has_nothrow_constructor">has_nothrow_constructor</link>.
      </para>
    </section>
    <section id="boost_typetraits.reference.has_trivial_assign"><indexterm type="class_name"><primary>has_trivial_assign</primary><secondary>has_trivial_assign</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.has_trivial_assign"> has_trivial_assign</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">has_trivial_assign</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If T is a (possibly cv-qualified)
        type with a trivial assignment-operator then inherits from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
      </para>
      <para>
        If a type has a trivial assignment-operator then the operator has the same
        effect as copying the bits of one object to the other: calls to the operator
        can be safely replaced with a call to <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">memcpy</phrase></computeroutput>.
      </para>
      <para>
        <emphasis role="bold">Compiler Compatibility:</emphasis> If the compiler
        does not support partial-specialization of class templates, then this template
        can not be used with function types.
      </para>
      <para>
        Without some (as yet unspecified) help from the compiler, has_trivial_assign
        will never report that a user-defined class or struct has a trivial constructor;
        this is always safe, if possibly sub-optimal. Currently (May 2005) only MWCW
        9 and Visual C++ 8 have the necessary compiler <link linkend="boost_typetraits.intrinsics">intrinsics</link>
        to detect user-defined classes with trivial constructors.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 12.8p11.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">has_trivial_assign</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Examples:</emphasis>
      </para>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">has_trivial_assign</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">&gt;</phrase></computeroutput>
            inherits from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">has_trivial_assign</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">char</phrase><phrase role="special">*&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">has_trivial_assign</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="special">(*)(</phrase><phrase role="keyword">long</phrase><phrase role="special">)&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">has_trivial_assign</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">MyClass</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>false</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">has_trivial_assign</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">bool</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
    </section>
    <section id="boost_typetraits.reference.has_trivial_constructor"><indexterm type="class_name"><primary>has_trivial_default_constructor</primary><secondary>has_trivial_constructor</secondary></indexterm><indexterm><primary>has_trivial_constructor</primary><secondary>has_trivial_default_constructor</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.has_trivial_constructor">
      has_trivial_constructor</link></title> 
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">has_trivial_constructor</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">has_trivial_default_constructor</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If T is a (possibly cv-qualified)
        type with a trivial default-constructor then inherits from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
      </para>
      <para>
        These two traits are synonyms for each other.
      </para>
      <para>
        If a type has a trivial default-constructor then the constructor have no
        effect: calls to the constructor can be safely omitted. Note that using meta-programming
        to omit a call to a single trivial-constructor call is of no benefit whatsoever.
        However, if loops and/or exception handling code can also be omitted, then
        some benefit in terms of code size and speed can be obtained.
      </para>
      <para>
        <emphasis role="bold">Compiler Compatibility:</emphasis> If the compiler
        does not support partial-specialization of class templates, then this template
        can not be used with function types.
      </para>
      <para>
        Without some (as yet unspecified) help from the compiler, has_trivial_constructor
        will never report that a user-defined class or struct has a trivial constructor;
        this is always safe, if possibly sub-optimal. Currently (May 2005) only MWCW
        9 and Visual C++ 8 have the necessary compiler <link linkend="boost_typetraits.intrinsics">intrinsics</link>
        to detect user-defined classes with trivial constructors.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 12.1p6.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">has_trivial_constructor</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Examples:</emphasis>
      </para>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">has_trivial_constructor</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">&gt;</phrase></computeroutput> inherits from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">has_trivial_constructor</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">char</phrase><phrase role="special">*&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">has_trivial_constructor</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="special">(*)(</phrase><phrase role="keyword">long</phrase><phrase role="special">)&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput>
            is an integral constant expression that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">has_trivial_constructor</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">MyClass</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput>
            is an integral constant expression that evaluates to <emphasis>false</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">has_trivial_constructor</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase></computeroutput>
            is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">bool</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
    </section>
    <section id="boost_typetraits.reference.has_trivial_copy"><indexterm type="class_name"><primary>has_trivial_copy_constructor</primary><secondary>has_trivial_copy</secondary></indexterm><indexterm><primary>has_trivial_copy</primary><secondary>has_trivial_copy_constructor</secondary></indexterm><indexterm type="class_name"><primary>has_trivial_copy</primary><secondary>has_trivial_copy</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.has_trivial_copy"> has_trivial_copy</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">has_trivial_copy</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>

<phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">has_trivial_copy_constructor</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If T is a (possibly cv-qualified)
        type with a trivial copy-constructor then inherits from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
      </para>
      <para>
        These two traits are synonyms for each other.
      </para>
      <para>
        If a type has a trivial copy-constructor then the constructor has the same
        effect as copying the bits of one object to the other: calls to the constructor
        can be safely replaced with a call to <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">memcpy</phrase></computeroutput>.
      </para>
      <para>
        <emphasis role="bold">Compiler Compatibility:</emphasis> If the compiler
        does not support partial-specialization of class templates, then this template
        can not be used with function types.
      </para>
      <para>
        Without some (as yet unspecified) help from the compiler, has_trivial_copy
        will never report that a user-defined class or struct has a trivial constructor;
        this is always safe, if possibly sub-optimal. Currently (May 2005) only MWCW
        9 and Visual C++ 8 have the necessary compiler <link linkend="boost_typetraits.intrinsics">intrinsics</link>
        to detect user-defined classes with trivial constructors.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 12.8p6.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">has_trivial_copy</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Examples:</emphasis>
      </para>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">has_trivial_copy</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">&gt;</phrase></computeroutput>
            inherits from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">has_trivial_copy</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">char</phrase><phrase role="special">*&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">has_trivial_copy</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="special">(*)(</phrase><phrase role="keyword">long</phrase><phrase role="special">)&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">has_trivial_copy</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">MyClass</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>false</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">has_trivial_copy</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">bool</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
    </section>
    <section id="boost_typetraits.reference.has_trivial_cp_cons">
      <title><link linkend="boost_typetraits.reference.has_trivial_cp_cons"> has_trivial_copy_constructor</link></title>
      <para>
        See <link linkend="boost_typetraits.reference.has_trivial_copy">has_trivial_copy</link>.
      </para>
    </section>
    <section id="boost_typetraits.reference.has_trivial_def_cons">
      <title><link linkend="boost_typetraits.reference.has_trivial_def_cons"> has_trivial_default_constructor</link></title>
      <para>
        See <link linkend="boost_typetraits.reference.has_trivial_constructor">has_trivial_constructor</link>.
      </para>
    </section>
    <section id="boost_typetraits.reference.has_trivial_destructor"><indexterm type="class_name"><primary>has_trivial_destructor</primary><secondary>has_trivial_destructor</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.has_trivial_destructor"> has_trivial_destructor</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">has_trivial_destructor</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If T is a (possibly cv-qualified)
        type with a trivial destructor then inherits from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
      </para>
      <para>
        If a type has a trivial destructor then the destructor has no effect: calls
        to the destructor can be safely omitted. Note that using meta-programming
        to omit a call to a single trivial-constructor call is of no benefit whatsoever.
        However, if loops and/or exception handling code can also be omitted, then
        some benefit in terms of code size and speed can be obtained.
      </para>
      <para>
        <emphasis role="bold">Compiler Compatibility:</emphasis> If the compiler
        does not support partial-specialization of class templates, then this template
        can not be used with function types.
      </para>
      <para>
        Without some (as yet unspecified) help from the compiler, has_trivial_destructor
        will never report that a user-defined class or struct has a trivial destructor;
        this is always safe, if possibly sub-optimal. Currently (May 2005) only MWCW
        9 and Visual C++ 8 have the necessary compiler <link linkend="boost_typetraits.intrinsics">intrinsics</link>
        to detect user-defined classes with trivial constructors.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 12.4p3.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">has_trivial_destructor</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Examples:</emphasis>
      </para>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">has_trivial_destructor</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">&gt;</phrase></computeroutput> inherits from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">has_trivial_destructor</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">char</phrase><phrase role="special">*&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">has_trivial_destructor</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="special">(*)(</phrase><phrase role="keyword">long</phrase><phrase role="special">)&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput>
            is an integral constant expression that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">has_trivial_destructor</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">MyClass</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput>
            is an integral constant expression that evaluates to <emphasis>false</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">has_trivial_destructor</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase></computeroutput>
            is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">bool</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
    </section>
    <section id="boost_typetraits.reference.has_virtual_destructor"><indexterm type="class_name"><primary>has_virtual_destructor</primary><secondary>has_virtual_destructor</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.has_virtual_destructor"> has_virtual_destructor</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">has_virtual_destructor</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If T is a (possibly cv-qualified)
        type with a virtual destructor then inherits from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
      </para>
      <para>
        <emphasis role="bold">Compiler Compatibility:</emphasis> This trait is provided
        for completeness, since it's part of the Technical Report on C++ Library
        Extensions. However, there is currently no way to portably implement this
        trait. The default version provided always inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>,
        and has to be explicitly specialized for types with virtual destructors unless
        the compiler used has compiler <link linkend="boost_typetraits.intrinsics">intrinsics</link>
        that enable the trait to do the right thing: currently (May 2005) only Visual
        C++ 8 and GCC-4.3 have the necessary <link linkend="boost_typetraits.intrinsics">intrinsics</link>.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 12.4.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">has_virtual_destructor</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
    </section>
    <section id="boost_typetraits.reference.integral_constant"><indexterm type="typedef_name"><primary>value_type</primary><secondary>integral_constant</secondary></indexterm><indexterm><primary>integral_constant</primary><secondary>value_type</secondary></indexterm><indexterm type="typedef_name"><primary>true_type</primary><secondary>integral_constant</secondary></indexterm><indexterm><primary>integral_constant</primary><secondary>true_type</secondary></indexterm><indexterm type="class_name"><primary>integral_constant</primary><secondary>integral_constant</secondary></indexterm><indexterm type="typedef_name"><primary>false_type</primary><secondary>integral_constant</secondary></indexterm><indexterm><primary>integral_constant</primary><secondary>false_type</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.integral_constant"> integral_constant</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">,</phrase> <phrase role="identifier">T</phrase> <phrase role="identifier">val</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">integral_constant</phrase>
<phrase role="special">{</phrase>
   <phrase role="keyword">typedef</phrase> <phrase role="identifier">integral_constant</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">,</phrase> <phrase role="identifier">val</phrase><phrase role="special">&gt;</phrase>  <phrase role="identifier">type</phrase><phrase role="special">;</phrase>
   <phrase role="keyword">typedef</phrase> <phrase role="identifier">T</phrase>                          <phrase role="identifier">value_type</phrase><phrase role="special">;</phrase>
   <phrase role="keyword">static</phrase> <phrase role="keyword">const</phrase> <phrase role="identifier">T</phrase> <phrase role="identifier">value</phrase> <phrase role="special">=</phrase> <phrase role="identifier">val</phrase><phrase role="special">;</phrase>
<phrase role="special">};</phrase>

<phrase role="keyword">typedef</phrase> <phrase role="identifier">integral_constant</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">bool</phrase><phrase role="special">,</phrase> <phrase role="keyword">true</phrase><phrase role="special">&gt;</phrase>  <phrase role="identifier">true_type</phrase><phrase role="special">;</phrase>
<phrase role="keyword">typedef</phrase> <phrase role="identifier">integral_constant</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">bool</phrase><phrase role="special">,</phrase> <phrase role="keyword">false</phrase><phrase role="special">&gt;</phrase> <phrase role="identifier">false_type</phrase><phrase role="special">;</phrase>
</programlisting>
      <para>
        Class template <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">integral_constant</phrase></computeroutput>
        is the common base class for all the value-based type traits. The two typedef's
        <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">true_type</phrase></computeroutput> and <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">false_type</phrase></computeroutput> are provided for convenience:
        most of the value traits are Boolean properties and so will inherit from
        one of these.
      </para>
    </section>
    <section id="boost_typetraits.reference.integral_promotion"><indexterm type="class_name"><primary>integral_promotion</primary><secondary>integral_promotion</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.integral_promotion"> integral_promotion</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">integral_promotion</phrase>
<phrase role="special">{</phrase>
   <phrase role="keyword">typedef</phrase> <replaceable>see-below</replaceable> <phrase role="identifier">type</phrase><phrase role="special">;</phrase>
<phrase role="special">};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">type:</emphasis> If integral promotion can be applied
        to an rvalue of type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>, then
        applies integral promotion to <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>
        and keeps cv-qualifiers of <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>,
        otherwise leaves <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput> unchanged.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 4.5 except 4.5/3
        (integral bit-field).
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">integral_promotion</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <table frame="all"> <title>Examples</title>
      <tgroup cols="2">
        <thead>
          <row>
            <entry>
            <para>
              Expression
            </para>
            </entry><entry>
            <para>
              Result Type
            </para>
            </entry>
          </row>
        </thead>
        <tbody>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">integral_promotion</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">short</phrase>
              <phrase role="keyword">const</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">integral_promotion</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">short</phrase><phrase role="special">&amp;&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">short</phrase><phrase role="special">&amp;</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">integral_promotion</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">enum</phrase> <phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">float_round_style</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase></computeroutput>
            </para>
            </entry>
          </row>
        </tbody>
      </tgroup>
      </table>
    </section>
    <section id="boost_typetraits.reference.is_abstract"><indexterm type="class_name"><primary>is_abstract</primary><secondary>is_abstract</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.is_abstract"> is_abstract</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">is_abstract</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If T is a (possibly cv-qualified)
        abstract type then inherits from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 10.3.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">is_abstract</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Compiler Compatibility:</emphasis> The compiler must
        support DR337 (as of April 2005: GCC 3.4, VC++ 7.1 (and later), Intel C++
        7 (and later), and Comeau 4.3.2). Otherwise behaves the same as <link linkend="boost_typetraits.reference.is_polymorphic">is_polymorphic</link>;
        this is the "safe fallback position" for which polymorphic types
        are always regarded as potentially abstract. The macro BOOST_NO_IS_ABSTRACT
        is used to signify that the implementation is buggy, users should check for
        this in their own code if the "safe fallback" is not suitable for
        their particular use-case.
      </para>
      <para>
        <emphasis role="bold">Examples:</emphasis>
      </para>
      <blockquote>
        <para>
          <para>
            Given: <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">class</phrase> <phrase role="identifier">abc</phrase><phrase role="special">{</phrase> <phrase role="keyword">virtual</phrase> <phrase role="special">~</phrase><phrase role="identifier">abc</phrase><phrase role="special">()</phrase> <phrase role="special">=</phrase> <phrase role="number">0</phrase><phrase role="special">;</phrase> <phrase role="special">};</phrase></computeroutput>
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_abstract</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">abc</phrase><phrase role="special">&gt;</phrase></computeroutput>
            inherits from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_abstract</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">abc</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_abstract</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">abc</phrase> <phrase role="keyword">const</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput>
            is an integral constant expression that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_abstract</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">bool</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
    </section>
    <section id="boost_typetraits.reference.is_arithmetic"><indexterm type="class_name"><primary>is_arithmetic</primary><secondary>is_arithmetic</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.is_arithmetic"> is_arithmetic</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">is_arithmetic</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If T is a (possibly cv-qualified)
        arithmetic type then inherits from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
        Arithmetic types include integral and floating point types (see also <link linkend="boost_typetraits.reference.is_integral">is_integral</link> and
        <link linkend="boost_typetraits.reference.is_floating_point">is_floating_point</link>).
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 3.9.1p8.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">is_arithmetic</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Examples:</emphasis>
      </para>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_arithmetic</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">&gt;</phrase></computeroutput>
            inherits from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_arithmetic</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">char</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_arithmetic</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">double</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_arithmetic</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">bool</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
    </section>
    <section id="boost_typetraits.reference.is_array"><indexterm type="class_name"><primary>is_array</primary><secondary>is_array</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.is_array"> is_array</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">is_array</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If T is a (possibly cv-qualified)
        array type then inherits from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 3.9.2 and 8.3.4.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">is_array</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Compiler Compatibility:</emphasis> If the compiler
        does not support partial-specialization of class templates, then this template
        can give the wrong result with function types.
      </para>
      <para>
        <emphasis role="bold">Examples:</emphasis>
      </para>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_array</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">[</phrase><phrase role="number">2</phrase><phrase role="special">]&gt;</phrase></computeroutput> inherits from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_array</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">char</phrase><phrase role="special">[</phrase><phrase role="number">2</phrase><phrase role="special">][</phrase><phrase role="number">3</phrase><phrase role="special">]&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_array</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">double</phrase><phrase role="special">[]&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_array</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">bool</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
    </section>
    <section id="boost_typetraits.reference.is_base_of"><indexterm type="class_name"><primary>is_base_of</primary><secondary>is_base_of</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.is_base_of"> is_base_of</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">Base</phrase><phrase role="special">,</phrase> <phrase role="keyword">class</phrase> <phrase role="identifier">Derived</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">is_base_of</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If Base is base class of type
        Derived or if both types are the same then inherits from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
      </para>
      <para>
        This template will detect non-public base classes, and ambiguous base classes.
      </para>
      <para>
        Note that <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_base_of</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">X</phrase><phrase role="special">,</phrase><phrase role="identifier">X</phrase><phrase role="special">&gt;</phrase></computeroutput> will always inherit from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>.
        <emphasis role="bold">This is the case even if <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">X</phrase></computeroutput>
        is not a class type</emphasis>. This is a change in behaviour from Boost-1.33
        in order to track the Technical Report on C++ Library Extensions.
      </para>
      <para>
        Types <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">Base</phrase></computeroutput> and <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">Derived</phrase></computeroutput> must not be incomplete types.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 10.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">is_base_of</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Compiler Compatibility:</emphasis> If the compiler
        does not support partial-specialization of class templates, then this template
        can not be used with function types. There are some older compilers which
        will produce compiler errors if <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">Base</phrase></computeroutput>
        is a private base class of <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">Derived</phrase></computeroutput>,
        or if <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">Base</phrase></computeroutput> is an ambiguous
        base of <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">Derived</phrase></computeroutput>. These compilers
        include Borland C++, older versions of Sun Forte C++, Digital Mars C++, and
        older versions of EDG based compilers.
      </para>
      <para>
        <emphasis role="bold">Examples:</emphasis>
      </para>
      <blockquote>
        <para>
          <para>
            Given: <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="keyword">class</phrase> <phrase role="identifier">Base</phrase><phrase role="special">{};</phrase> <phrase role="keyword">class</phrase> <phrase role="identifier">Derived</phrase> <phrase role="special">:</phrase>
            <phrase role="keyword">public</phrase> <phrase role="identifier">Base</phrase><phrase role="special">{};</phrase></computeroutput>
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_base_of</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">Base</phrase><phrase role="special">,</phrase> <phrase role="identifier">Derived</phrase><phrase role="special">&gt;</phrase></computeroutput>
            inherits from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_base_of</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">Base</phrase><phrase role="special">,</phrase> <phrase role="identifier">Derived</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_base_of</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">Base</phrase><phrase role="special">,</phrase> <phrase role="identifier">Derived</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_base_of</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">Base</phrase><phrase role="special">,</phrase> <phrase role="identifier">Derived</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_base_of</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">Base</phrase><phrase role="special">,</phrase> <phrase role="identifier">Base</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>true</emphasis>: a class is regarded as it's
            own base.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_base_of</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">bool</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
    </section>
    <section id="boost_typetraits.reference.is_class"><indexterm type="class_name"><primary>is_class</primary><secondary>is_class</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.is_class"> is_class</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">is_class</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If T is a (possibly cv-qualified)
        class type then inherits from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 3.9.2 and 9.2.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">is_class</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Compiler Compatibility:</emphasis> Without (some as
        yet unspecified) help from the compiler, we cannot distinguish between union
        and class types, as a result this type will erroneously inherit from <link linkend="boost_typetraits.reference.integral_constant">true_type</link> for
        union types. See also <link linkend="boost_typetraits.reference.is_union">is_union</link>.
        Currently (May 2005) only Visual C++ 8 has the necessary compiler <link linkend="boost_typetraits.intrinsics">intrinsics</link>
        to correctly identify union types, and therefore make is_class function correctly.
      </para>
      <para>
        <emphasis role="bold">Examples:</emphasis>
      </para>
      <blockquote>
        <para>
          <para>
            Given: <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">class</phrase> <phrase role="identifier">MyClass</phrase><phrase role="special">;</phrase></computeroutput> then:
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_class</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">MyClass</phrase><phrase role="special">&gt;</phrase></computeroutput>
            inherits from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_class</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">MyClass</phrase> <phrase role="keyword">const</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_class</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">MyClass</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_class</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">MyClass</phrase><phrase role="special">&amp;&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>false</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_class</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">MyClass</phrase><phrase role="special">*&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>false</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_class</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">bool</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
    </section>
    <section id="boost_typetraits.reference.is_complex"><indexterm type="class_name"><primary>is_complex</primary><secondary>is_complex</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.is_complex"> is_complex</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">is_complex</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>
        is a complex number type then true (of type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">complex</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">U</phrase><phrase role="special">&gt;</phrase></computeroutput>
        for some type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">U</phrase></computeroutput>), otherwise
        false.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 26.2.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">is_complex</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
    </section>
    <section id="boost_typetraits.reference.is_compound"><indexterm type="class_name"><primary>is_compound</primary><secondary>is_compound</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.is_compound"> is_compound</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">is_compound</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If T is a (possibly cv-qualified)
        compound type then inherits from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
        Any type that is not a fundamental type is a compound type (see also <link linkend="boost_typetraits.reference.is_fundamental">is_fundamental</link>).
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 3.9.2.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">is_compound</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Examples:</emphasis>
      </para>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_compound</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">MyClass</phrase><phrase role="special">&gt;</phrase></computeroutput>
            inherits from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_compound</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">MyEnum</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_compound</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">*&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_compound</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">&amp;&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_compound</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>false</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_compound</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">bool</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
    </section>
    <section id="boost_typetraits.reference.is_const"><indexterm type="class_name"><primary>is_const</primary><secondary>is_const</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.is_const"> is_const</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">is_const</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If T is a (top level) const-qualified
        type then inherits from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 3.9.3.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">is_const</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Examples:</emphasis>
      </para>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_const</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase><phrase role="special">&gt;</phrase></computeroutput> inherits from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_const</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase> <phrase role="keyword">volatile</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_const</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">*</phrase> <phrase role="keyword">const</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_const</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase><phrase role="special">*&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput>
            is an integral constant expression that evaluates to <emphasis>false</emphasis>:
            the const-qualifier is not at the top level in this case.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_const</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase><phrase role="special">&amp;&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput>
            is an integral constant expression that evaluates to <emphasis>false</emphasis>:
            the const-qualifier is not at the top level in this case.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_const</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>false</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_const</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">bool</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
    </section>
    <section id="boost_typetraits.reference.is_convertible"><indexterm type="class_name"><primary>is_convertible</primary><secondary>is_convertible</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.is_convertible"> is_convertible</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">From</phrase><phrase role="special">,</phrase> <phrase role="keyword">class</phrase> <phrase role="identifier">To</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">is_convertible</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If an imaginary lvalue of type
        <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">From</phrase></computeroutput> is convertible to type
        <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">To</phrase></computeroutput> then inherits from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
      </para>
      <para>
        Type From must not be an incomplete type.
      </para>
      <para>
        Type To must not be an incomplete, or function type.
      </para>
      <para>
        No types are considered to be convertible to array types or abstract-class
        types.
      </para>
      <para>
        This template can not detect whether a converting-constructor is <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">public</phrase></computeroutput> or not: if type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">To</phrase></computeroutput>
        has a <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">private</phrase></computeroutput> converting constructor
        from type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">From</phrase></computeroutput> then instantiating
        <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_convertible</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">From</phrase><phrase role="special">,</phrase> <phrase role="identifier">To</phrase><phrase role="special">&gt;</phrase></computeroutput>
        will produce a compiler error. For this reason <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_convertible</phrase></computeroutput>
        can not be used to determine whether a type has a <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">public</phrase></computeroutput>
        copy-constructor or not.
      </para>
      <para>
        This template will also produce compiler errors if the conversion is ambiguous,
        for example:
      </para>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">struct</phrase> <phrase role="identifier">A</phrase> <phrase role="special">{};</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">B</phrase> <phrase role="special">:</phrase> <phrase role="identifier">A</phrase> <phrase role="special">{};</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">C</phrase> <phrase role="special">:</phrase> <phrase role="identifier">A</phrase> <phrase role="special">{};</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">D</phrase> <phrase role="special">:</phrase> <phrase role="identifier">B</phrase><phrase role="special">,</phrase> <phrase role="identifier">C</phrase> <phrase role="special">{};</phrase>
<phrase role="comment">// This produces a compiler error, the conversion is ambiguous:
</phrase><phrase role="keyword">bool</phrase> <phrase role="keyword">const</phrase> <phrase role="identifier">y</phrase> <phrase role="special">=</phrase> <phrase role="identifier">boost</phrase><phrase role="special">::</phrase><phrase role="identifier">is_convertible</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">D</phrase><phrase role="special">*,</phrase><phrase role="identifier">A</phrase><phrase role="special">*&gt;::</phrase><phrase role="identifier">value</phrase><phrase role="special">;</phrase>
</programlisting>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 4 and 8.5.
      </para>
      <para>
        <emphasis role="bold">Compiler Compatibility:</emphasis> This template is
        currently broken with Borland C++ Builder 5 (and earlier), for constructor-based
        conversions, and for the Metrowerks 7 (and earlier) compiler in all cases.
        If the compiler does not support <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.is_abstract">is_abstract</link></computeroutput>,
        then the template parameter <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">To</phrase></computeroutput>
        must not be an abstract type.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">is_convertible</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Examples:</emphasis>
      </para>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_convertible</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">,</phrase> <phrase role="keyword">double</phrase><phrase role="special">&gt;</phrase></computeroutput>
            inherits from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_convertible</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">const</phrase> <phrase role="keyword">int</phrase><phrase role="special">,</phrase> <phrase role="keyword">double</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_convertible</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">*</phrase> <phrase role="keyword">const</phrase><phrase role="special">,</phrase> <phrase role="keyword">int</phrase><phrase role="special">*&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_convertible</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase><phrase role="special">*,</phrase> <phrase role="keyword">int</phrase><phrase role="special">*&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput>
            is an integral constant expression that evaluates to <emphasis>false</emphasis>:
            the conversion would require a <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">const_cast</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_convertible</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase><phrase role="special">&amp;,</phrase> <phrase role="keyword">long</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput>
            is an integral constant expression that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_convertible</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>false</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_convertible</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">bool</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
    </section>
    <section id="boost_typetraits.reference.is_empty"><indexterm type="class_name"><primary>is_empty</primary><secondary>is_empty</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.is_empty"> is_empty</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">is_empty</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If T is an empty class type then
        inherits from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 10p5.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">is_empty</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Compiler Compatibility:</emphasis> In order to correctly
        detect empty classes this trait relies on either:
      </para>
      <itemizedlist>
        <listitem>
          the compiler implementing zero sized empty base classes, or
        </listitem>
        <listitem>
          the compiler providing <link linkend="boost_typetraits.intrinsics">intrinsics</link>
          to detect empty classes.
        </listitem>
      </itemizedlist>
      <para>
        Can not be used with incomplete types.
      </para>
      <para>
        Can not be used with union types, until is_union can be made to work.
      </para>
      <para>
        If the compiler does not support partial-specialization of class templates,
        then this template can not be used with abstract types.
      </para>
      <para>
        <emphasis role="bold">Examples:</emphasis>
      </para>
      <blockquote>
        <para>
          <para>
            Given: <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">struct</phrase> <phrase role="identifier">empty_class</phrase>
            <phrase role="special">{};</phrase></computeroutput>
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_empty</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">empty_class</phrase><phrase role="special">&gt;</phrase></computeroutput>
            inherits from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_empty</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">empty_class</phrase> <phrase role="keyword">const</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_empty</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">empty_class</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_empty</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">bool</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
    </section>
    <section id="boost_typetraits.reference.is_enum"><indexterm type="class_name"><primary>is_enum</primary><secondary>is_enum</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.is_enum"> is_enum</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">is_enum</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If T is a (possibly cv-qualified)
        enum type then inherits from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 3.9.2 and 7.2.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">is_enum</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Compiler Compatibility:</emphasis> Requires a correctly
        functioning <link linkend="boost_typetraits.reference.is_convertible">is_convertible</link>
        template; this means that is_enum is currently broken under Borland C++ Builder
        5, and for the Metrowerks compiler prior to version 8, other compilers should
        handle this template just fine.
      </para>
      <para>
        <emphasis role="bold">Examples:</emphasis>
      </para>
      <blockquote>
        <para>
          <para>
            Given: <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">enum</phrase> <phrase role="identifier">my_enum</phrase>
            <phrase role="special">{</phrase> <phrase role="identifier">one</phrase><phrase role="special">,</phrase> <phrase role="identifier">two</phrase> <phrase role="special">};</phrase></computeroutput>
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_enum</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">my_enum</phrase><phrase role="special">&gt;</phrase></computeroutput>
            inherits from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_enum</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">my_enum</phrase> <phrase role="keyword">const</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_enum</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">my_enum</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_enum</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">my_enum</phrase><phrase role="special">&amp;&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>false</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_enum</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">my_enum</phrase><phrase role="special">*&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>false</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_enum</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">bool</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
    </section>
    <section id="boost_typetraits.reference.is_floating_point"><indexterm type="class_name"><primary>is_floating_point</primary><secondary>is_floating_point</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.is_floating_point"> is_floating_point</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">is_floating_point</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If T is a (possibly cv-qualified)
        floating point type then inherits from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 3.9.1p8.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">is_floating_point</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Examples:</emphasis>
      </para>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_floating_point</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">float</phrase><phrase role="special">&gt;</phrase></computeroutput>
            inherits from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_floating_point</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">double</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_floating_point</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">long</phrase> <phrase role="keyword">double</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput>
            is an integral constant expression that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_floating_point</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">bool</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
    </section>
    <section id="boost_typetraits.reference.is_function"><indexterm type="class_name"><primary>is_function</primary><secondary>is_function</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.is_function"> is_function</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">is_function</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If T is a (possibly cv-qualified)
        function type then inherits from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
        Note that this template does not detect <emphasis>pointers to functions</emphasis>,
        or <emphasis>references to functions</emphasis>, these are detected by <link linkend="boost_typetraits.reference.is_pointer">is_pointer</link> and <link linkend="boost_typetraits.reference.is_reference">is_reference</link> respectively:
      </para>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">typedef</phrase> <phrase role="keyword">int</phrase> <phrase role="identifier">f1</phrase><phrase role="special">();</phrase>      <phrase role="comment">// f1 is of function type.
</phrase><phrase role="keyword">typedef</phrase> <phrase role="keyword">int</phrase> <phrase role="special">(</phrase><phrase role="identifier">f2</phrase><phrase role="special">*)();</phrase>   <phrase role="comment">// f2 is a pointer to a function.
</phrase><phrase role="keyword">typedef</phrase> <phrase role="keyword">int</phrase> <phrase role="special">(</phrase><phrase role="identifier">f3</phrase><phrase role="special">&amp;)();</phrase>   <phrase role="comment">// f3 is a reference to a function.
</phrase></programlisting>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 3.9.2p1 and 8.3.5.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">is_function</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Examples:</emphasis>
      </para>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_function</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="special">(</phrase><phrase role="keyword">void</phrase><phrase role="special">)&gt;</phrase></computeroutput>
            inherits from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_function</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">long</phrase> <phrase role="special">(</phrase><phrase role="keyword">double</phrase><phrase role="special">,</phrase> <phrase role="keyword">int</phrase><phrase role="special">)&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_function</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">long</phrase> <phrase role="special">(</phrase><phrase role="keyword">double</phrase><phrase role="special">,</phrase> <phrase role="keyword">int</phrase><phrase role="special">)&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_function</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">long</phrase> <phrase role="special">(*)(</phrase><phrase role="keyword">double</phrase><phrase role="special">,</phrase> <phrase role="keyword">int</phrase><phrase role="special">)&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>false</emphasis>: the argument in this case
            is a pointer type, not a function type.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_function</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">long</phrase> <phrase role="special">(&amp;)(</phrase><phrase role="keyword">double</phrase><phrase role="special">,</phrase> <phrase role="keyword">int</phrase><phrase role="special">)&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>false</emphasis>: the argument in this case
            is a reference to a function, not a function type.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_function</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">long</phrase> <phrase role="special">(</phrase><phrase role="identifier">MyClass</phrase><phrase role="special">::*)(</phrase><phrase role="keyword">double</phrase><phrase role="special">,</phrase> <phrase role="keyword">int</phrase><phrase role="special">)&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>false</emphasis>: the argument in this case
            is a pointer to a member function.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_function</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">bool</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
      <tip>
        <para>
          Don't confuse function-types with pointers to functions:
        </para>
        <para>
          <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">typedef</phrase> <phrase role="keyword">int</phrase>
          <phrase role="identifier">f</phrase><phrase role="special">(</phrase><phrase role="keyword">double</phrase><phrase role="special">);</phrase></computeroutput>
        </para>
        <para>
          defines a function type,
        </para>
        <para>
          <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">f</phrase> <phrase role="identifier">foo</phrase><phrase role="special">;</phrase></computeroutput>
        </para>
        <para>
          declares a prototype for a function of type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">f</phrase></computeroutput>,
        </para>
        <para>
          <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">f</phrase><phrase role="special">*</phrase>
          <phrase role="identifier">pf</phrase> <phrase role="special">=</phrase>
          <phrase role="identifier">foo</phrase><phrase role="special">;</phrase></computeroutput>
        </para>
        <para>
          <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">f</phrase><phrase role="special">&amp;</phrase>
          <phrase role="identifier">fr</phrase> <phrase role="special">=</phrase>
          <phrase role="identifier">foo</phrase><phrase role="special">;</phrase></computeroutput>
        </para>
        <para>
          declares a pointer and a reference to the function <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">foo</phrase></computeroutput>.
        </para>
        <para>
          If you want to detect whether some type is a pointer-to-function then use:
        </para>
        <para>
          <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.is_function">is_function</link><phrase role="special">&lt;</phrase><link linkend="boost_typetraits.reference.remove_pointer">remove_pointer</link><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase>
          <phrase role="special">&amp;&amp;</phrase> <link linkend="boost_typetraits.reference.is_pointer">is_pointer</link><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput>
        </para>
        <para>
          or for pointers to member functions you can just use <link linkend="boost_typetraits.reference.is_member_function_pointer">is_member_function_pointer</link>
          directly.
        </para>
      </tip>
    </section>
    <section id="boost_typetraits.reference.is_fundamental"><indexterm type="class_name"><primary>is_fundamental</primary><secondary>is_fundamental</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.is_fundamental"> is_fundamental</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">is_fundamental</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If T is a (possibly cv-qualified)
        fundamental type then inherits from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
        Fundamental types include integral, floating point and void types (see also
        <link linkend="boost_typetraits.reference.is_integral">is_integral</link>,
        <link linkend="boost_typetraits.reference.is_floating_point">is_floating_point</link>
        and <link linkend="boost_typetraits.reference.is_void">is_void</link>)
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 3.9.1.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">is_fundamental</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Examples:</emphasis>
      </para>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_fundamental</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">)&gt;</phrase></computeroutput>
            inherits from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_fundamental</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">double</phrase> <phrase role="keyword">const</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_fundamental</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">void</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_fundamental</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">bool</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
    </section>
    <section id="boost_typetraits.reference.is_integral"><indexterm type="class_name"><primary>is_integral</primary><secondary>is_integral</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.is_integral"> is_integral</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">is_integral</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If T is a (possibly cv-qualified)
        integral type then inherits from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 3.9.1p7.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">is_integral</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Examples:</emphasis>
      </para>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_integral</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">&gt;</phrase></computeroutput>
            inherits from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_integral</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">const</phrase> <phrase role="keyword">char</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_integral</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">long</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_integral</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">bool</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
    </section>
    <section id="boost_typetraits.reference.is_member_function_pointer"><indexterm type="class_name"><primary>is_member_function_pointer</primary><secondary>is_member_function_pointer</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.is_member_function_pointer">
      is_member_function_pointer</link></title> 
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">is_member_function_pointer</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If T is a (possibly cv-qualified)
        pointer to a member function then inherits from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 3.9.2 and 8.3.3.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">is_member_function_pointer</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Examples:</emphasis>
      </para>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_member_function_pointer</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="special">(</phrase><phrase role="identifier">MyClass</phrase><phrase role="special">::*)(</phrase><phrase role="keyword">void</phrase><phrase role="special">)&gt;</phrase></computeroutput> inherits from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_member_function_pointer</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="special">(</phrase><phrase role="identifier">MyClass</phrase><phrase role="special">::*)(</phrase><phrase role="keyword">char</phrase><phrase role="special">)&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_member_function_pointer</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="special">(</phrase><phrase role="identifier">MyClass</phrase><phrase role="special">::*)(</phrase><phrase role="keyword">void</phrase><phrase role="special">)</phrase><phrase role="keyword">const</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput>
            is an integral constant expression that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_member_function_pointer</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="special">(</phrase><phrase role="identifier">MyClass</phrase><phrase role="special">::*)&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput>
            is an integral constant expression that evaluates to <emphasis>false</emphasis>:
            the argument in this case is a pointer to a data member and not a member
            function, see <link linkend="boost_typetraits.reference.is_member_object_pointer">is_member_object_pointer</link>
            and <link linkend="boost_typetraits.reference.is_member_pointer">is_member_pointer</link>
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_member_function_pointer</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase></computeroutput>
            is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">bool</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
    </section>
    <section id="boost_typetraits.reference.is_member_object_pointer"><indexterm type="class_name"><primary>is_member_object_pointer</primary><secondary>is_member_object_pointer</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.is_member_object_pointer">
      is_member_object_pointer</link></title> 
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">is_member_object_pointer</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If T is a (possibly cv-qualified)
        pointer to a member object (a data member) then inherits from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 3.9.2 and 8.3.3.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">is_member_object_pointer</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Examples:</emphasis>
      </para>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_member_object_pointer</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="special">(</phrase><phrase role="identifier">MyClass</phrase><phrase role="special">::*)&gt;</phrase></computeroutput> inherits from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_member_object_pointer</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">double</phrase> <phrase role="special">(</phrase><phrase role="identifier">MyClass</phrase><phrase role="special">::*)&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_member_object_pointer</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">const</phrase> <phrase role="keyword">int</phrase> <phrase role="special">(</phrase><phrase role="identifier">MyClass</phrase><phrase role="special">::*)&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_member_object_pointer</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="special">(</phrase><phrase role="identifier">MyClass</phrase><phrase role="special">::*)(</phrase><phrase role="keyword">void</phrase><phrase role="special">)&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput>
            is an integral constant expression that evaluates to <emphasis>false</emphasis>:
            the argument in this case is a pointer to a member function and not a
            member object, see <link linkend="boost_typetraits.reference.is_member_function_pointer">is_member_function_pointer</link>
            and <link linkend="boost_typetraits.reference.is_member_pointer">is_member_pointer</link>
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_member_object_pointer</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase></computeroutput>
            is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">bool</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
    </section>
    <section id="boost_typetraits.reference.is_member_pointer"><indexterm type="class_name"><primary>is_member_pointer</primary><secondary>is_member_pointer</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.is_member_pointer"> is_member_pointer</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">is_member_pointer</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If T is a (possibly cv-qualified)
        pointer to a member (either a function or a data member) then inherits from
        <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 3.9.2 and 8.3.3.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">is_member_pointer</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Examples:</emphasis>
      </para>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_member_pointer</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="special">(</phrase><phrase role="identifier">MyClass</phrase><phrase role="special">::*)&gt;</phrase></computeroutput>
            inherits from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_member_pointer</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="special">(</phrase><phrase role="identifier">MyClass</phrase><phrase role="special">::*)(</phrase><phrase role="keyword">char</phrase><phrase role="special">)&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_member_pointer</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="special">(</phrase><phrase role="identifier">MyClass</phrase><phrase role="special">::*)(</phrase><phrase role="keyword">void</phrase><phrase role="special">)</phrase><phrase role="keyword">const</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_member_pointer</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">bool</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
    </section>
    <section id="boost_typetraits.reference.is_object"><indexterm type="class_name"><primary>is_object</primary><secondary>is_object</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.is_object"> is_object</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">is_object</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If T is a (possibly cv-qualified)
        object type then inherits from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
        All types are object types except references, void, and function types.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 3.9p9.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">is_object</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Examples:</emphasis>
      </para>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_object</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">&gt;</phrase></computeroutput>
            inherits from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_object</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">*&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_object</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="special">(*)(</phrase><phrase role="keyword">void</phrase><phrase role="special">)&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_object</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="special">(</phrase><phrase role="identifier">MyClass</phrase><phrase role="special">::*)(</phrase><phrase role="keyword">void</phrase><phrase role="special">)</phrase><phrase role="keyword">const</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_object</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="special">&amp;&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>false</emphasis>: reference types are not
            objects
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_object</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="special">(</phrase><phrase role="keyword">double</phrase><phrase role="special">)&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>false</emphasis>: function types are not
            objects
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_object</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">const</phrase> <phrase role="keyword">void</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput>
            is an integral constant expression that evaluates to <emphasis>false</emphasis>:
            void is not an object type
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_object</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">bool</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
    </section>
    <section id="boost_typetraits.reference.is_pod">
      <title><link linkend="boost_typetraits.reference.is_pod"> is_pod</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">is_pod</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If T is a (possibly cv-qualified)
        POD type then inherits from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
      </para>
      <para>
        POD stands for "Plain old data". Arithmetic types, and enumeration
        types, a pointers and pointer to members are all PODs. Classes and unions
        can also be POD's if they have no non-static data members that are of reference
        or non-POD type, no user defined constructors, no user defined assignment
        operators, no private or protected non-static data members, no virtual functions
        and no base classes. Finally, a cv-qualified POD is still a POD, as is an
        array of PODs.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 3.9p10 and 9p4 (Note
        that POD's are also aggregates, see 8.5.1).
      </para>
      <para>
        <emphasis role="bold">Compiler Compatibility:</emphasis> If the compiler
        does not support partial-specialization of class templates, then this template
        can not be used with function types.
      </para>
      <para>
        Without some (as yet unspecified) help from the compiler, is<emphasis role="underline">pod
        will never report that a class or struct is a POD; this is always safe, if
        possibly sub-optimal. Currently (May 2005) only MWCW 9 and Visual C++ 8 have
        the necessary compiler-</emphasis>_intrinsics.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">is_pod</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Examples:</emphasis>
      </para>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_pod</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">&gt;</phrase></computeroutput>
            inherits from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_pod</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">char</phrase><phrase role="special">*&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_pod</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="special">(*)(</phrase><phrase role="keyword">long</phrase><phrase role="special">)&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_pod</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">MyClass</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>false</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_pod</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">bool</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
    </section>
    <section id="boost_typetraits.reference.is_pointer"><indexterm type="class_name"><primary>is_pointer</primary><secondary>is_pointer</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.is_pointer"> is_pointer</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">is_pointer</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If T is a (possibly cv-qualified)
        pointer type (includes function pointers, but excludes pointers to members)
        then inherits from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 3.9.2p2 and 8.3.1.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">is_pointer</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Examples:</emphasis>
      </para>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_pointer</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">*&gt;</phrase></computeroutput>
            inherits from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_pointer</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">char</phrase><phrase role="special">*</phrase> <phrase role="keyword">const</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_pointer</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="special">(*)(</phrase><phrase role="keyword">long</phrase><phrase role="special">)&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_pointer</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="special">(</phrase><phrase role="identifier">MyClass</phrase><phrase role="special">::*)(</phrase><phrase role="keyword">long</phrase><phrase role="special">)&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>false</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_pointer</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="special">(</phrase><phrase role="identifier">MyClass</phrase><phrase role="special">::*)&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>false</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_pointer</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">bool</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
      <important>
        <para>
          <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_pointer</phrase></computeroutput> detects "real"
          pointer types only, and <emphasis>not</emphasis> smart pointers. Users
          should not specialise <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_pointer</phrase></computeroutput>
          for smart pointer types, as doing so may cause Boost (and other third party)
          code to fail to function correctly. Users wanting a trait to detect smart
          pointers should create their own. However, note that there is no way in
          general to auto-magically detect smart pointer types, so such a trait would
          have to be partially specialised for each supported smart pointer type.
        </para>
      </important>
    </section>
    <section id="boost_typetraits.reference.is_polymorphic"><indexterm type="class_name"><primary>is_polymorphic</primary><secondary>is_polymorphic</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.is_polymorphic"> is_polymorphic</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">is_polymorphic</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If T is a (possibly cv-qualified)
        polymorphic type then inherits from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
        Type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput> must be a complete
        type.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 10.3.
      </para>
      <para>
        <emphasis role="bold">Compiler Compatibility:</emphasis> The implementation
        requires some knowledge of the compilers ABI, it does actually seem to work
        with the majority of compilers though.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">is_polymorphic</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Examples:</emphasis>
      </para>
      <blockquote>
        <para>
          <para>
            Given: <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">class</phrase> <phrase role="identifier">poly</phrase><phrase role="special">{</phrase> <phrase role="keyword">virtual</phrase> <phrase role="special">~</phrase><phrase role="identifier">poly</phrase><phrase role="special">();</phrase> <phrase role="special">};</phrase></computeroutput>
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_polymorphic</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">poly</phrase><phrase role="special">&gt;</phrase></computeroutput>
            inherits from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_polymorphic</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">poly</phrase> <phrase role="keyword">const</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_polymorphic</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">poly</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_polymorphic</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">bool</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
    </section>
    <section id="boost_typetraits.reference.is_same"><indexterm type="class_name"><primary>is_same</primary><secondary>is_same</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.is_same"> is_same</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">,</phrase> <phrase role="keyword">class</phrase> <phrase role="identifier">U</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">is_same</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If T and U are the same types
        then inherits from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">is_same</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Compiler Compatibility:</emphasis> If the compiler
        does not support partial-specialization of class templates, then this template
        can not be used with abstract, incomplete or function types.
      </para>
      <para>
        <emphasis role="bold">Examples:</emphasis>
      </para>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_same</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">,</phrase> <phrase role="keyword">int</phrase><phrase role="special">&gt;</phrase></computeroutput>
            inherits from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_same</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">,</phrase> <phrase role="keyword">int</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_same</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">,</phrase> <phrase role="keyword">int</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_same</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase><phrase role="special">,</phrase> <phrase role="keyword">int</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput>
            is an integral constant expression that evaluates to <emphasis>false</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_same</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">&amp;,</phrase> <phrase role="keyword">int</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>false</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_same</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">bool</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
    </section>
    <section id="boost_typetraits.reference.is_scalar"><indexterm type="class_name"><primary>is_scalar</primary><secondary>is_scalar</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.is_scalar"> is_scalar</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">is_scalar</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If T is a (possibly cv-qualified)
        scalar type then inherits from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
        Scalar types include integral, floating point, enumeration, pointer, and
        pointer-to-member types.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 3.9p10.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">is_scalar</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Compiler Compatibility:</emphasis> If the compiler
        does not support partial-specialization of class templates, then this template
        can not be used with function types.
      </para>
      <para>
        <emphasis role="bold">Examples:</emphasis>
      </para>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_scalar</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">*&gt;</phrase></computeroutput>
            inherits from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_scalar</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_scalar</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">double</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_scalar</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="special">(*)(</phrase><phrase role="keyword">long</phrase><phrase role="special">)&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_scalar</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="special">(</phrase><phrase role="identifier">MyClass</phrase><phrase role="special">::*)(</phrase><phrase role="keyword">long</phrase><phrase role="special">)&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_scalar</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="special">(</phrase><phrase role="identifier">MyClass</phrase><phrase role="special">::*)&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_scalar</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">bool</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
    </section>
    <section id="boost_typetraits.reference.is_signed"><indexterm type="class_name"><primary>is_signed</primary><secondary>is_signed</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.is_signed"> is_signed</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">is_signed</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If T is an signed integer type
        or an enumerated type with an underlying signed integer type, then inherits
        from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 3.9.1, 7.2.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">is_signed</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Examples:</emphasis>
      </para>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_signed</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">&gt;</phrase></computeroutput>
            inherits from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_signed</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase> <phrase role="keyword">volatile</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_signed</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">unsigned</phrase> <phrase role="keyword">int</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput>
            is an integral constant expression that evaluates to <emphasis>false</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_signed</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">myclass</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>false</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_signed</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">char</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            whose value depends upon the signedness of type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">char</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_signed</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">long</phrase> <phrase role="keyword">long</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput>
            is an integral constant expression that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_signed</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">bool</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
    </section>
    <section id="boost_typetraits.reference.is_stateless">
      <title><link linkend="boost_typetraits.reference.is_stateless"> is_stateless</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">is_stateless</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> Ff T is a stateless type then
        inherits from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
      </para>
      <para>
        Type T must be a complete type.
      </para>
      <para>
        A stateless type is a type that has no storage and whose constructors and
        destructors are trivial. That means that <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_stateless</phrase></computeroutput>
        only inherits from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>
        if the following expression is <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">true</phrase></computeroutput>:
      </para>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="special">::</phrase><phrase role="identifier">boost</phrase><phrase role="special">::</phrase><phrase role="identifier">has_trivial_constructor</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase>
<phrase role="special">&amp;&amp;</phrase> <phrase role="special">::</phrase><phrase role="identifier">boost</phrase><phrase role="special">::</phrase><phrase role="identifier">has_trivial_copy</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase>
<phrase role="special">&amp;&amp;</phrase> <phrase role="special">::</phrase><phrase role="identifier">boost</phrase><phrase role="special">::</phrase><phrase role="identifier">has_trivial_destructor</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase>
<phrase role="special">&amp;&amp;</phrase> <phrase role="special">::</phrase><phrase role="identifier">boost</phrase><phrase role="special">::</phrase><phrase role="identifier">is_class</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase>
<phrase role="special">&amp;&amp;</phrase> <phrase role="special">::</phrase><phrase role="identifier">boost</phrase><phrase role="special">::</phrase><phrase role="identifier">is_empty</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase>
</programlisting>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 3.9p10.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">is_stateless</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Compiler Compatibility:</emphasis> If the compiler
        does not support partial-specialization of class templates, then this template
        can not be used with function types.
      </para>
      <para>
        Without some (as yet unspecified) help from the compiler, is_stateless will
        never report that a class or struct is stateless; this is always safe, if
        possibly sub-optimal. Currently (May 2005) only MWCW 9 and Visual C++ 8 have
        the necessary compiler <link linkend="boost_typetraits.intrinsics">intrinsics</link>
        to make this template work automatically.
      </para>
    </section>
    <section id="boost_typetraits.reference.is_reference"><indexterm type="class_name"><primary>is_reference</primary><secondary>is_reference</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.is_reference"> is_reference</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">is_reference</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If T is a reference pointer type
        then inherits from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 3.9.2 and 8.3.2.
      </para>
      <para>
        <emphasis role="bold">Compiler Compatibility:</emphasis> If the compiler
        does not support partial-specialization of class templates, then this template
        may report the wrong result for function types, and for types that are both
        const and volatile qualified.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">is_reference</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Examples:</emphasis>
      </para>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_reference</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">&amp;&gt;</phrase></computeroutput>
            inherits from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_reference</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase><phrase role="special">&amp;&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_reference</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="special">(&amp;)(</phrase><phrase role="keyword">long</phrase><phrase role="special">)&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>true</emphasis> (the argument in this case
            is a reference to a function).
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_reference</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">bool</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
    </section>
    <section id="boost_typetraits.reference.is_union"><indexterm type="class_name"><primary>is_union</primary><secondary>is_union</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.is_union"> is_union</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">is_union</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If T is a (possibly cv-qualified)
        union type then inherits from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
        Currently requires some kind of compiler support, otherwise unions are identified
        as classes.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 3.9.2 and 9.5.
      </para>
      <para>
        <emphasis role="bold">Compiler Compatibility:</emphasis> Without (some as
        yet unspecified) help from the compiler, we cannot distinguish between union
        and class types using only standard C++, as a result this type will never
        inherit from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        unless the user explicitly specializes the template for their user-defined
        union types, or unless the compiler supplies some unspecified intrinsic that
        implements this functionality. Currently (May 2005) only Visual C++ 8 has
        the necessary compiler <link linkend="boost_typetraits.intrinsics">intrinsics</link>
        to make this trait "just work" without user intervention.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">is_union</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Examples:</emphasis>
      </para>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_union</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">void</phrase><phrase role="special">&gt;</phrase></computeroutput>
            inherits from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_union</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">const</phrase> <phrase role="keyword">void</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_union</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">void</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_union</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">void</phrase><phrase role="special">*&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>false</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_union</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">bool</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
    </section>
    <section id="boost_typetraits.reference.is_unsigned"><indexterm type="class_name"><primary>is_unsigned</primary><secondary>is_unsigned</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.is_unsigned"> is_unsigned</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">is_unsigned</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If T is an unsigned integer type
        or an enumerated type with an underlying unsigned integer type, then inherits
        from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 3.9.1, 7.2.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">is_unsigned</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Examples:</emphasis>
      </para>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_unsigned</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">unsigned</phrase> <phrase role="keyword">int</phrase><phrase role="special">&gt;</phrase></computeroutput> inherits from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_unsigned</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">unsigned</phrase> <phrase role="keyword">int</phrase>
            <phrase role="keyword">const</phrase> <phrase role="keyword">volatile</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_unsigned</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>false</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_unsigned</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">myclass</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>false</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_unsigned</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">char</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            whose value depends upon the signedness of type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">char</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_unsigned</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">unsigned</phrase> <phrase role="keyword">long</phrase>
            <phrase role="keyword">long</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_unsigned</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">bool</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
    </section>
    <section id="boost_typetraits.reference.is_void"><indexterm type="class_name"><primary>is_void</primary><secondary>is_void</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.is_void"> is_void</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">is_void</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If T is a (possibly cv-qualified)
        void type then inherits from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 3.9.1p9.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">is_void</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Examples:</emphasis>
      </para>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_void</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">void</phrase><phrase role="special">&gt;</phrase></computeroutput>
            inherits from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_void</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">const</phrase> <phrase role="keyword">void</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_void</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">void</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_void</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">void</phrase><phrase role="special">*&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>false</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_void</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">bool</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
    </section>
    <section id="boost_typetraits.reference.is_volatile"><indexterm type="class_name"><primary>is_volatile</primary><secondary>is_volatile</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.is_volatile"> is_volatile</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">is_volatile</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <replaceable><link linkend="boost_typetraits.reference.integral_constant">true_type</link>-or-<link linkend="boost_typetraits.reference.integral_constant">false_type</link></replaceable> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> If T is a (top level) volatile-qualified
        type then inherits from <link linkend="boost_typetraits.reference.integral_constant">true_type</link>,
        otherwise inherits from <link linkend="boost_typetraits.reference.integral_constant">false_type</link>.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 3.9.3.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">is_volatile</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Examples:</emphasis>
      </para>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_volatile</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">volatile</phrase> <phrase role="keyword">int</phrase><phrase role="special">&gt;</phrase></computeroutput> inherits from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_volatile</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">const</phrase> <phrase role="keyword">volatile</phrase>
            <phrase role="keyword">int</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">true_type</link></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_volatile</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">*</phrase> <phrase role="keyword">volatile</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>true</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_volatile</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="keyword">volatile</phrase><phrase role="special">*&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput>
            is an integral constant expression that evaluates to <emphasis>false</emphasis>:
            the volatile qualifier is not at the top level in this case.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">is_volatile</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">bool</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
    </section>
    <section id="boost_typetraits.reference.make_signed"><indexterm type="class_name"><primary>make_signed</primary><secondary>make_signed</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.make_signed"> make_signed</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">make_signed</phrase>
<phrase role="special">{</phrase>
   <phrase role="keyword">typedef</phrase> <replaceable>see-below</replaceable> <phrase role="identifier">type</phrase><phrase role="special">;</phrase>
<phrase role="special">};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">type:</emphasis> If T is a signed integer type then
        the same type as T, if T is an unsigned integer type then the corresponding
        signed type. Otherwise if T is an enumerated or character type (char or wchar_t)
        then a signed integer type with the same width as T.
      </para>
      <para>
        If T has any cv-qualifiers then these are also present on the result type.
      </para>
      <para>
        <emphasis role="bold">Requires:</emphasis> T must be an integer or enumerated
        type, and must not be the type bool.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 3.9.1.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">make_signed</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <table frame="all"> <title>Examples</title>
      <tgroup cols="2">
        <thead>
          <row>
            <entry>
            <para>
              Expression
            </para>
            </entry><entry>
            <para>
              Result Type
            </para>
            </entry>
          </row>
        </thead>
        <tbody>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">make_signed</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">make_signed</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">unsigned</phrase> <phrase role="keyword">int</phrase>
              <phrase role="keyword">const</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">make_signed</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">const</phrase> <phrase role="keyword">unsigned</phrase>
              <phrase role="keyword">long</phrase> <phrase role="keyword">long</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">const</phrase> <phrase role="keyword">long</phrase>
              <phrase role="keyword">long</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">make_signed</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">my_enum</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              A signed integer type with the same width as the enum.
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">make_signed</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">wchar_t</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              A signed integer type with the same width as wchar_t.
            </para>
            </entry>
          </row>
        </tbody>
      </tgroup>
      </table>
    </section>
    <section id="boost_typetraits.reference.make_unsigned"><indexterm type="class_name"><primary>make_unsigned</primary><secondary>make_unsigned</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.make_unsigned"> make_unsigned</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">make_unsigned</phrase>
<phrase role="special">{</phrase>
   <phrase role="keyword">typedef</phrase> <replaceable>see-below</replaceable> <phrase role="identifier">type</phrase><phrase role="special">;</phrase>
<phrase role="special">};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">type:</emphasis> If T is a unsigned integer type then
        the same type as T, if T is an signed integer type then the corresponding
        unsigned type. Otherwise if T is an enumerated or character type (char or
        wchar_t) then an unsigned integer type with the same width as T.
      </para>
      <para>
        If T has any cv-qualifiers then these are also present on the result type.
      </para>
      <para>
        <emphasis role="bold">Requires:</emphasis> T must be an integer or enumerated
        type, and must not be the type bool.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 3.9.1.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">make_unsigned</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <table frame="all"> <title>Examples</title>
      <tgroup cols="2">
        <thead>
          <row>
            <entry>
            <para>
              Expression
            </para>
            </entry><entry>
            <para>
              Result Type
            </para>
            </entry>
          </row>
        </thead>
        <tbody>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">make_signed</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">unsigned</phrase> <phrase role="keyword">int</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">make_signed</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">unsigned</phrase> <phrase role="keyword">int</phrase>
              <phrase role="keyword">const</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">unsigned</phrase> <phrase role="keyword">int</phrase>
              <phrase role="keyword">const</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">make_signed</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">const</phrase> <phrase role="keyword">unsigned</phrase>
              <phrase role="keyword">long</phrase> <phrase role="keyword">long</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">const</phrase> <phrase role="keyword">unsigned</phrase>
              <phrase role="keyword">long</phrase> <phrase role="keyword">long</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">make_signed</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">my_enum</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              An unsigned integer type with the same width as the enum.
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">make_signed</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">wchar_t</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              An unsigned integer type with the same width as wchar_t.
            </para>
            </entry>
          </row>
        </tbody>
      </tgroup>
      </table>
    </section>
    <section id="boost_typetraits.reference.promote"><indexterm type="class_name"><primary>promote</primary><secondary>promote</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.promote"> promote</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">promote</phrase>
<phrase role="special">{</phrase>
   <phrase role="keyword">typedef</phrase> <replaceable>see-below</replaceable> <phrase role="identifier">type</phrase><phrase role="special">;</phrase>
<phrase role="special">};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">type:</emphasis> If integral or floating point promotion
        can be applied to an rvalue of type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>,
        then applies integral and floating point promotions to <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>
        and keeps cv-qualifiers of <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>,
        otherwise leaves <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput> unchanged.
        See also <link linkend="boost_typetraits.reference.integral_promotion">integral_promotion</link>
        and <link linkend="boost_typetraits.reference.floating_point_promotion">floating_point_promotion</link>.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 4.5 except 4.5/3
        (integral bit-field) and 4.6.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">promote</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <table frame="all"> <title>Examples</title>
      <tgroup cols="2">
        <thead>
          <row>
            <entry>
            <para>
              Expression
            </para>
            </entry><entry>
            <para>
              Result Type
            </para>
            </entry>
          </row>
        </thead>
        <tbody>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">promote</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">short</phrase> <phrase role="keyword">volatile</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase> <phrase role="keyword">volatile</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">promote</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">float</phrase> <phrase role="keyword">const</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">double</phrase> <phrase role="keyword">const</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">promote</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">short</phrase><phrase role="special">&amp;&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">short</phrase><phrase role="special">&amp;</phrase></computeroutput>
            </para>
            </entry>
          </row>
        </tbody>
      </tgroup>
      </table>
    </section>
    <section id="boost_typetraits.reference.rank"><indexterm type="class_name"><primary>integral_constant</primary><secondary>rank</secondary></indexterm><indexterm><primary>rank</primary><secondary>integral_constant</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.rank"> rank</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">rank</phrase> <phrase role="special">:</phrase> <phrase role="keyword">public</phrase> <link linkend="boost_typetraits.reference.integral_constant">integral_constant</link><phrase role="special">&lt;</phrase><phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">size_t</phrase><phrase role="special">,</phrase> <phrase role="identifier">RANK</phrase><phrase role="special">(</phrase><phrase role="identifier">T</phrase><phrase role="special">)&gt;</phrase> <phrase role="special">{};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">Inherits:</emphasis> Class template rank inherits from
        <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">integral_constant</link><phrase role="special">&lt;</phrase><phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">size_t</phrase><phrase role="special">,</phrase> <phrase role="identifier">RANK</phrase><phrase role="special">(</phrase><phrase role="identifier">T</phrase><phrase role="special">)&gt;</phrase></computeroutput>,
        where <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">RANK</phrase><phrase role="special">(</phrase><phrase role="identifier">T</phrase><phrase role="special">)</phrase></computeroutput> is the
        number of array dimensions in type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>.
      </para>
      <para>
        If <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput> is not an array type,
        then <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">RANK</phrase><phrase role="special">(</phrase><phrase role="identifier">T</phrase><phrase role="special">)</phrase></computeroutput> is zero.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">rank</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <para>
        <emphasis role="bold">Examples:</emphasis>
      </para>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">rank</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">[]&gt;</phrase></computeroutput>
            inherits from <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">integral_constant</link><phrase role="special">&lt;</phrase><phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">size_t</phrase><phrase role="special">,</phrase> <phrase role="number">1</phrase><phrase role="special">&gt;</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">rank</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">double</phrase><phrase role="special">[</phrase><phrase role="number">2</phrase><phrase role="special">][</phrase><phrase role="number">3</phrase><phrase role="special">][</phrase><phrase role="number">4</phrase><phrase role="special">]&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><link linkend="boost_typetraits.reference.integral_constant">integral_constant</link><phrase role="special">&lt;</phrase><phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">size_t</phrase><phrase role="special">,</phrase> <phrase role="number">3</phrase><phrase role="special">&gt;</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">rank</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">[</phrase><phrase role="number">1</phrase><phrase role="special">]&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput>
            is an integral constant expression that evaluates to <emphasis>1</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">rank</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">[][</phrase><phrase role="number">2</phrase><phrase role="special">]&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>2</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">rank</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">*&gt;::</phrase><phrase role="identifier">value</phrase></computeroutput> is an integral constant expression
            that evaluates to <emphasis>0</emphasis>.
          </para>
        </para>
      </blockquote>
      <blockquote>
        <para>
          <para>
            <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">rank</phrase><phrase role="special">&lt;</phrase><phrase role="identifier">T</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">value_type</phrase></computeroutput> is the type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">size_t</phrase></computeroutput>.
          </para>
        </para>
      </blockquote>
    </section>
    <section id="boost_typetraits.reference.remove_all_extents"><indexterm type="class_name"><primary>remove_all_extents</primary><secondary>remove_all_extents</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.remove_all_extents"> remove_all_extents</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">remove_all_extents</phrase>
<phrase role="special">{</phrase>
   <phrase role="keyword">typedef</phrase> <replaceable>see-below</replaceable> <phrase role="identifier">type</phrase><phrase role="special">;</phrase>
<phrase role="special">};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">type:</emphasis> If <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>
        is an array type, then removes all of the array bounds on <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>,
        otherwise leaves <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput> unchanged.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 8.3.4.
      </para>
      <para>
        <emphasis role="bold">Compiler Compatibility:</emphasis> If the compiler
        does not support partial specialization of class-templates then this template
        will compile, but the member <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">type</phrase></computeroutput>
        will always be the same as type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>
        except where <link linkend="boost_typetraits.category.transform.broken_compiler_workarounds_">compiler
        workarounds</link> have been applied.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">remove_all_extents</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <table frame="all"> <title>Examples</title>
      <tgroup cols="2">
        <thead>
          <row>
            <entry>
            <para>
              Expression
            </para>
            </entry><entry>
            <para>
              Result Type
            </para>
            </entry>
          </row>
        </thead>
        <tbody>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_all_extents</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_all_extents</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase><phrase role="special">[</phrase><phrase role="number">2</phrase><phrase role="special">]&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_all_extents</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">[][</phrase><phrase role="number">2</phrase><phrase role="special">]&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_all_extents</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">[</phrase><phrase role="number">2</phrase><phrase role="special">][</phrase><phrase role="number">3</phrase><phrase role="special">][</phrase><phrase role="number">4</phrase><phrase role="special">]&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_all_extents</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase><phrase role="special">*&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase><phrase role="special">*</phrase></computeroutput>
            </para>
            </entry>
          </row>
        </tbody>
      </tgroup>
      </table>
    </section>
    <section id="boost_typetraits.reference.remove_const"><indexterm type="class_name"><primary>remove_const</primary><secondary>remove_const</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.remove_const"> remove_const</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">remove_const</phrase>
<phrase role="special">{</phrase>
   <phrase role="keyword">typedef</phrase> <replaceable>see-below</replaceable> <phrase role="identifier">type</phrase><phrase role="special">;</phrase>
<phrase role="special">};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">type:</emphasis> The same type as <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>,
        but with any <emphasis>top level</emphasis> const-qualifier removed.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 3.9.3.
      </para>
      <para>
        <emphasis role="bold">Compiler Compatibility:</emphasis> If the compiler
        does not support partial specialization of class-templates then this template
        will compile, but the member <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">type</phrase></computeroutput>
        will always be the same as type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>
        except where <link linkend="boost_typetraits.category.transform.broken_compiler_workarounds_">compiler
        workarounds</link> have been applied.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">remove_const</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <table frame="all"> <title>Examples</title>
      <tgroup cols="2">
        <thead>
          <row>
            <entry>
            <para>
              Expression
            </para>
            </entry><entry>
            <para>
              Result Type
            </para>
            </entry>
          </row>
        </thead>
        <tbody>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_const</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_const</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_const</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase>
              <phrase role="keyword">volatile</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase> <phrase role="keyword">volatile</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_const</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase><phrase role="special">&amp;&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase><phrase role="special">&amp;</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_const</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase><phrase role="special">*&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase><phrase role="special">*</phrase></computeroutput>
            </para>
            </entry>
          </row>
        </tbody>
      </tgroup>
      </table>
    </section>
    <section id="boost_typetraits.reference.remove_cv"><indexterm type="class_name"><primary>remove_cv</primary><secondary>remove_cv</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.remove_cv"> remove_cv</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">remove_cv</phrase>
<phrase role="special">{</phrase>
   <phrase role="keyword">typedef</phrase> <replaceable>see-below</replaceable> <phrase role="identifier">type</phrase><phrase role="special">;</phrase>
<phrase role="special">};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">type:</emphasis> The same type as <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>,
        but with any <emphasis>top level</emphasis> cv-qualifiers removed.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 3.9.3.
      </para>
      <para>
        <emphasis role="bold">Compiler Compatibility:</emphasis> If the compiler
        does not support partial specialization of class-templates then this template
        will compile, but the member <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">type</phrase></computeroutput>
        will always be the same as type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>
        except where <link linkend="boost_typetraits.category.transform.broken_compiler_workarounds_">compiler
        workarounds</link> have been applied.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">remove_cv</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <table frame="all"> <title>Examples</title>
      <tgroup cols="2">
        <thead>
          <row>
            <entry>
            <para>
              Expression
            </para>
            </entry><entry>
            <para>
              Result Type
            </para>
            </entry>
          </row>
        </thead>
        <tbody>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_cv</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_cv</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_cv</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase>
              <phrase role="keyword">volatile</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_cv</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase><phrase role="special">&amp;&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase><phrase role="special">&amp;</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_cv</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase><phrase role="special">*&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase><phrase role="special">*</phrase></computeroutput>
            </para>
            </entry>
          </row>
        </tbody>
      </tgroup>
      </table>
    </section>
    <section id="boost_typetraits.reference.remove_extent"><indexterm type="class_name"><primary>remove_extent</primary><secondary>remove_extent</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.remove_extent"> remove_extent</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">remove_extent</phrase>
<phrase role="special">{</phrase>
   <phrase role="keyword">typedef</phrase> <replaceable>see-below</replaceable> <phrase role="identifier">type</phrase><phrase role="special">;</phrase>
<phrase role="special">};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">type:</emphasis> If <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>
        is an array type, then removes the topmost array bound, otherwise leaves
        <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput> unchanged.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 8.3.4.
      </para>
      <para>
        <emphasis role="bold">Compiler Compatibility:</emphasis> If the compiler
        does not support partial specialization of class-templates then this template
        will compile, but the member <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">type</phrase></computeroutput>
        will always be the same as type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>
        except where <link linkend="boost_typetraits.category.transform.broken_compiler_workarounds_">compiler
        workarounds</link> have been applied.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">remove_extent</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <table frame="all"> <title>Examples</title>
      <tgroup cols="2">
        <thead>
          <row>
            <entry>
            <para>
              Expression
            </para>
            </entry><entry>
            <para>
              Result Type
            </para>
            </entry>
          </row>
        </thead>
        <tbody>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_extent</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_extent</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase><phrase role="special">[</phrase><phrase role="number">2</phrase><phrase role="special">]&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_extent</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">[</phrase><phrase role="number">2</phrase><phrase role="special">][</phrase><phrase role="number">4</phrase><phrase role="special">]&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase><phrase role="special">[</phrase><phrase role="number">4</phrase><phrase role="special">]</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_extent</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">[][</phrase><phrase role="number">2</phrase><phrase role="special">]&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase><phrase role="special">[</phrase><phrase role="number">2</phrase><phrase role="special">]</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_extent</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase><phrase role="special">*&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase><phrase role="special">*</phrase></computeroutput>
            </para>
            </entry>
          </row>
        </tbody>
      </tgroup>
      </table>
    </section>
    <section id="boost_typetraits.reference.remove_pointer"><indexterm type="class_name"><primary>remove_pointer</primary><secondary>remove_pointer</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.remove_pointer"> remove_pointer</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">remove_pointer</phrase>
<phrase role="special">{</phrase>
   <phrase role="keyword">typedef</phrase> <replaceable>see-below</replaceable> <phrase role="identifier">type</phrase><phrase role="special">;</phrase>
<phrase role="special">};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">type:</emphasis> The same type as <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>,
        but with any pointer modifier removed.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 8.3.1.
      </para>
      <para>
        <emphasis role="bold">Compiler Compatibility:</emphasis> If the compiler
        does not support partial specialization of class-templates then this template
        will compile, but the member <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">type</phrase></computeroutput>
        will always be the same as type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>
        except where <link linkend="boost_typetraits.category.transform.broken_compiler_workarounds_">compiler
        workarounds</link> have been applied.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">remove_pointer</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <table frame="all"> <title>Examples</title>
      <tgroup cols="2">
        <thead>
          <row>
            <entry>
            <para>
              Expression
            </para>
            </entry><entry>
            <para>
              Result Type
            </para>
            </entry>
          </row>
        </thead>
        <tbody>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_pointer</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_pointer</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase><phrase role="special">*&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_pointer</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase><phrase role="special">**&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase><phrase role="special">*</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_pointer</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">&amp;&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase><phrase role="special">&amp;</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_pointer</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">*&amp;&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase><phrase role="special">*&amp;</phrase></computeroutput>
            </para>
            </entry>
          </row>
        </tbody>
      </tgroup>
      </table>
    </section>
    <section id="boost_typetraits.reference.remove_reference"><indexterm type="class_name"><primary>remove_reference</primary><secondary>remove_reference</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.remove_reference"> remove_reference</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">remove_reference</phrase>
<phrase role="special">{</phrase>
   <phrase role="keyword">typedef</phrase> <replaceable>see-below</replaceable> <phrase role="identifier">type</phrase><phrase role="special">;</phrase>
<phrase role="special">};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">type:</emphasis> The same type as <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>,
        but with any reference modifier removed.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 8.3.2.
      </para>
      <para>
        <emphasis role="bold">Compiler Compatibility:</emphasis> If the compiler
        does not support partial specialization of class-templates then this template
        will compile, but the member <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">type</phrase></computeroutput>
        will always be the same as type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>
        except where <link linkend="boost_typetraits.category.transform.broken_compiler_workarounds_">compiler
        workarounds</link> have been applied.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">remove_reference</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <table frame="all"> <title>Examples</title>
      <tgroup cols="2">
        <thead>
          <row>
            <entry>
            <para>
              Expression
            </para>
            </entry><entry>
            <para>
              Result Type
            </para>
            </entry>
          </row>
        </thead>
        <tbody>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_reference</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_reference</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase><phrase role="special">&amp;&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_reference</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">*&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase><phrase role="special">*</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_reference</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">*&amp;&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase><phrase role="special">*</phrase></computeroutput>
            </para>
            </entry>
          </row>
        </tbody>
      </tgroup>
      </table>
    </section>
    <section id="boost_typetraits.reference.remove_volatile"><indexterm type="class_name"><primary>remove_volatile</primary><secondary>remove_volatile</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.remove_volatile"> remove_volatile</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">remove_volatile</phrase>
<phrase role="special">{</phrase>
   <phrase role="keyword">typedef</phrase> <replaceable>see-below</replaceable> <phrase role="identifier">type</phrase><phrase role="special">;</phrase>
<phrase role="special">};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">type:</emphasis> The same type as <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>,
        but with any <emphasis>top level</emphasis> volatile-qualifier removed.
      </para>
      <para>
        <emphasis role="bold">C++ Standard Reference:</emphasis> 3.9.3.
      </para>
      <para>
        <emphasis role="bold">Compiler Compatibility:</emphasis> If the compiler
        does not support partial specialization of class-templates then this template
        will compile, but the member <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">type</phrase></computeroutput>
        will always be the same as type <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">T</phrase></computeroutput>
        except where <link linkend="boost_typetraits.category.transform.broken_compiler_workarounds_">compiler
        workarounds</link> have been applied.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">remove_volatile</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
      <table frame="all"> <title>Examples</title>
      <tgroup cols="2">
        <thead>
          <row>
            <entry>
            <para>
              Expression
            </para>
            </entry><entry>
            <para>
              Result Type
            </para>
            </entry>
          </row>
        </thead>
        <tbody>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_volatile</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_volatile</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="keyword">volatile</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_volatile</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase>
              <phrase role="keyword">volatile</phrase><phrase role="special">&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_volatile</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="keyword">volatile</phrase><phrase role="special">&amp;&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase><phrase role="special">&amp;</phrase></computeroutput>
            </para>
            </entry>
          </row>
          <row>
            <entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">remove_volatile</phrase><phrase role="special">&lt;</phrase><phrase role="keyword">int</phrase> <phrase role="keyword">volatile</phrase><phrase role="special">*&gt;::</phrase><phrase role="identifier">type</phrase></computeroutput>
            </para>
            </entry><entry>
            <para>
              <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">int</phrase> <phrase role="keyword">const</phrase><phrase role="special">*</phrase></computeroutput>
            </para>
            </entry>
          </row>
        </tbody>
      </tgroup>
      </table>
    </section>
    <section id="boost_typetraits.reference.type_with_alignment"><indexterm type="class_name"><primary>type_with_alignment</primary><secondary>type_with_alignment</secondary></indexterm>
      <title><link linkend="boost_typetraits.reference.type_with_alignment"> type_with_alignment</link></title>
      
<programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">std</phrase><phrase role="special">::</phrase><phrase role="identifier">size_t</phrase> <phrase role="identifier">Align</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">type_with_alignment</phrase>
<phrase role="special">{</phrase>
   <phrase role="keyword">typedef</phrase> <replaceable>see-below</replaceable> <phrase role="identifier">type</phrase><phrase role="special">;</phrase>
<phrase role="special">};</phrase>
</programlisting>
      <para>
        <emphasis role="bold">type:</emphasis> a built-in or POD type with an alignment
        that is a multiple of <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="identifier">Align</phrase></computeroutput>.
      </para>
      <para>
        <emphasis role="bold">Header:</emphasis> <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase>
        <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">/</phrase><phrase role="identifier">type_with_alignment</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
        or <computeroutput xmlns:xi="http://www.w3.org/2001/XInclude"> <phrase role="preprocessor">#include</phrase> <phrase role="special">&lt;</phrase><phrase role="identifier">boost</phrase><phrase role="special">/</phrase><phrase role="identifier">type_traits</phrase><phrase role="special">.</phrase><phrase role="identifier">hpp</phrase><phrase role="special">&gt;</phrase></computeroutput>
      </para>
    </section>
  </section>
  <section id="boost_typetraits.credits">
    <title><link linkend="boost_typetraits.credits"> Credits</link></title>
    <para>
      This documentation was pulled together by John Maddock, using <ulink url="../../../../doc/html/quickbook.html">Boost.Quickbook</ulink>
      and <ulink url="../../../../doc/html/boostbook.html">Boost.DocBook</ulink>.
    </para>
    <para>
      The original version of this library was created by Steve Cleary, Beman Dawes,
      Howard Hinnant, and John Maddock. John Maddock is the current maintainer of
      the library.
    </para>
    <para>
      This version of type traits library is based on contributions by Adobe Systems
      Inc, David Abrahams, Steve Cleary, Beman Dawes, Aleksey Gurtovoy, Howard Hinnant,
      Jesse Jones, Mat Marcus, Itay Maman, John Maddock, Thorsten Ottosen, Robert
      Ramey and Jeremy Siek.
    </para>
    <para>
      Mat Marcus and Jesse Jones invented, and <ulink url="http://opensource.adobe.com/project4/project.shtml">published
      a paper describing</ulink>, the partial specialization workarounds used in
      this library.
    </para>
    <para>
      Aleksey Gurtovoy added MPL integration to the library.
    </para>
    <para>
      The <link linkend="boost_typetraits.reference.is_convertible">is_convertible</link>
      template is based on code originally devised by Andrei Alexandrescu, see "<ulink url="http://www.cuj.com/experts/1810/alexandr.htm?topic=experts">Generic&lt;Programming&gt;:
      Mappings between Types and Values</ulink>".
    </para>
    <para>
      The latest version of this library and documentation can be found at <ulink url="http://www.boost.org">www.boost.org</ulink>. Bugs, suggestions and discussion
      should be directed to boost@lists.boost.org (see <ulink url="http://www.boost.org/more/mailing_lists.htm#main">www.boost.org/more/mailing_lists.htm#main</ulink>
      for subscription details).
    </para>
  </section>
   
  <section id="boost_typetraits.ignored_section">
    <title>This section must not be indexed.</title>
     <?BoostAutoIndex IgnoreSection?>
       <programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">add_const</phrase>
<phrase role="special">{</phrase>
   <phrase role="keyword">typedef</phrase> <replaceable>see-below</replaceable> <phrase role="identifier">type</phrase><phrase role="special">;</phrase>
<phrase role="special">};</phrase>
</programlisting>
  </section>

  <section id="boost_typetraits.ignored_block"><indexterm type="class_name"><primary>add_volatile</primary><secondary>This section contains one block that must not be indexed and one that should be.</secondary></indexterm><indexterm><primary>This section contains one block that must not be indexed and one that should be.</primary><secondary>add_volatile</secondary></indexterm>
    <title>This section contains one block that must not be indexed and one that should be.</title>
       <programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">
     <?BoostAutoIndex IgnoreBlock?>
          template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">add_const</phrase>
<phrase role="special">{</phrase>
   <phrase role="keyword">typedef</phrase> <replaceable>see-below</replaceable> <phrase role="identifier">type</phrase><phrase role="special">;</phrase>
<phrase role="special">};</phrase>
</programlisting>
       <programlisting xmlns:xi="http://www.w3.org/2001/XInclude"><phrase role="keyword">
          template</phrase> <phrase role="special">&lt;</phrase><phrase role="keyword">class</phrase> <phrase role="identifier">T</phrase><phrase role="special">&gt;</phrase>
<phrase role="keyword">struct</phrase> <phrase role="identifier">add_volatile</phrase>
<phrase role="special">{</phrase>
   <phrase role="keyword">typedef</phrase> <replaceable>see-below</replaceable> <phrase role="identifier">type</phrase><phrase role="special">;</phrase>
<phrase role="special">};</phrase>
</programlisting>
  </section>

  
    <index type="class_name">
  <title>Class Index</title>
  </index>
  <index type="typedef_name">
  <title>Typedef Index</title>
  </index>
  <index type="macro_name">
  <title>Macro Index</title>
  </index>
     <index type="test_index_1">
        <title>Index Test 1</title>
     </index>
     <index type="test_index_2">
        <title>Index Test 2</title>
     </index>
     <index/>
  
</chapter>